Slammers Coaches and Instructors

Our team of professional Coaches and instructors take pride in helping players of all ages and skill levels enhance their playing experience. Our goal is to provide every player a solid foundation to work from, as well as an understanding of the mechanics involved at each position. In addition, we want every player to have the opportunity to reach their maximum potential.

Mark Holzemer


Mark is a proud Littleton native and President of Slammers Baseball & Softball. Mark is former Major League left-handed pitcher who was drafted in the 4th round of the 1987 draft after graduating from Mullen High School. Mark played at Seminole Junior College in 1988 where he pitched in the Junior College World Series and earned 1st team All-American honors. Mark began his 15 year professional career with the California Angels in 1988 where he was both a starter and relief pitcher.

In addition to the Angels he pitched in the major leagues for the Seattle Mariners, Oakland Athletics and Philadelphia Phillies as well as playing for the Yokahama Baystars in the Japanese Major Leagues in 2001. Mark played three seasons of winter ball in Venezuela and one season in Mexico. Upon retiring in 2002 Mark became co-owner of Slammers baseball & Softball.

Mark’s passion is working with players of all ages to teach them the great game of baseball. Since joining the Slammers organization Mark has given more than 7000 private lessons and multiple camps and clinics. Mark has coached 6 year old teams through High School select teams. Marks teams have won the 9,12,13 and 14 USSSA Majors State Championships and he finished 5th in Cooperstown. He has competed with the Slammers teams in National tournaments across the country. Mark is currently an associate Scout for the Kansas City Royals.

Clint Zavaras


Clint Zavaras is a Colorado native who pitched at Mullen High School. His accolades coming out of high school include Dr. Pepper Player of the year and Colorado high school player of the year. He was acquired in the 3rd round by the Seattle Mariners of the 1985 draft. Clint made his major league debut against the Texas Rangers and Nolan Ryan in 1989. He signed with the Colorado Rockies in 1993.

Clint finished career with the Seattle Mariners in 1995. Clint was honored by being the opening day starting for the Greek National Team in the 2004 Olympics. Clint has spent the last 15 years giving private instruction to the areas top high school, college, and professional players and has done well over 20,000 private lessons. Clint is a pioneer in the bio-mechanics of pitching; developing one of the nations top Arm Velocity Programs. Clint is an owner of Slammers and a Associate Scout for the Kansas City Royals.

Billy Martin


Billy Martin played 4 years at the University of Texas at Arlington. He was drafted in the 34th round by the New York Mets. Taken in the rule 5 draft by the Arizona Diamondbacks in 1999 and then sold to the Yakult Swallows of the Japanese Central league in 2003. He was later signed by the Washington Nationals for the 2005 season.

Billy was a 3 time minor league all-star with a career .285 avg. and 94 home runs. Billy played 8 years professionally at 4 positions(1b,3b,lf,rf). Billy is now a owner, COO, and full time instructor/coach at Slammers. He specializes in hitting and fielding at all levels and works with youth pitchers as well. Billy has a bachelors degree in kinesiology from the University of Texas at Arlington and a MBA from CU Denver. Billy is also a certified National Strength and Conditioning(NSCA)personal trainer.

Billy is currently an Associate Scout for the Kansas City Royals.

John Cronican

John was a D1 baseball player at the University of New Mexico (1987-1990) and graduated with a Bachelor’s of Science in Management. Coach Cronican has been the Assistant Baseball Coach at Highlands Ranch High School (2004), Head Coach at Palmer Ridge High School (2008-2010), and most recently he was the Head Coach at Rock Canyon High School (2010-2013).

John joined Slammers in 2014 as a High School Summer coach, instructor, and recruiting and youth development coordinator.

Danny Sheridan

Danny Sheridan attended Cherry Creek High School, where he was 1 of 4 players ever to play Varsity baseball all 4 years. Danny was selected as a freshmen to compete for Team USA 17U to play in Italy against other countries top teams. Danny was also the starting CF for the Colorado Top 40 team.

After High School Danny turned down the Detroit Tigers and decided to sign at South Mountain CC in Phoenix and also Long Beach State in California. Before leaving his Father was diagnosed with cancer. Instead of pursuing baseball he decided to stay by his Father’s side. Danny has taught players from as early as 5 years old all the way up to Professional players. He teaches hitting, pitching, and fielding. He was also the head coach of an high school all star fall team this past year. Danny is currently as lead hitting instructor and Slammers High School Coach.

Marc Johnson


In the summer of 1971 Marc Johnson returned from Fort Hood, Texas where he served in the Army as Head coach of the 2nd armored division baseball team. He was then hired as the assistant varsity baseball coach at Cherry Creek High School in Greenwood Village, Colorado. One year later he took over the fledgling baseball program. His first year as the head coach the Bruins finished with a losing record. That was the first and last team he ever coached to a losing season.

His record as a head coach at Cherry Creek high School is 631 wins and 147 losses. Coach Johnson has coached his teams to 25 league titles and 11 state title games. Coach Johnson has won seven state championships in baseball. Marc was also the head soccer coach at Cherry Creek from 1971-1997 where he won five state championships.

Coach Johnson’s summer Connie Mack teams have made appearances in the AABC World Series three times. In 1987-88 Coach Johnson was the assistant coach of the USA Junior National team that won silver and gold medals in international play. In 2004 coach Johnson was named as the head coach of the USA Junior National team that competed in Taiwan. Coach Johnson has coached over 300 young men that have gone on to play at the collegiate level, 75 of which have gone on to play at the professional level. Five of his former players are currently playing in the major leagues.

Coach Johnson was named the Volunteer Summer Baseball coach of the year in 1988 by the United States Baseball Federation. In 1996 he was named High School coach of the year by the ABCA. In 1997 coach Johnson was named National Coach of the year by the American Amateur Baseball Congress. In 2000 Coach Johnson was named as one of the National Coaches of the decade by Baseball America. Coach Johnson has been named the coach of the year in Colorado seven times.

In 2004 coach Johnson received the Colorado Rockies Pioneer Award in 2004. In 2007 coach Johnson was inducted into the Colorado High School Coaches Association Hall of Fame. In 2010 coach Johnson was inducted into the Colorado High School Baseball Coaches Hall of Fame. That same year he was inducted into the prestigious Colorado Sports Hall of Fame whose membership includes professional and amateur athletes and coaches.

Coach Johnson has been a guest speaker at many state conventions and two National ABCA conventions. In January 2011 Coach Johnson will be inducted into the American Baseball Coaches Association Hall of Fame at their national convention in Nashville TN.

To say that Coach Johnson is a Colorado coaching legend is an understatement. His knowledge of the game and coaching style has touched many young lives and he continues to teach young players and coaches today. Coach Johnson is currently a scout for the Colorado Rockies and has scouted professionally for over 25 years and for the past nine years has been the executive director of The Yard and Marc Johnsons Sports Center, baseball and softball academy. Marc Johnson has been married to his wife Peggy for forty years. They have two adult children, Kerry and Tyler as well as four wonderful grandchildren.

Bryant Asnicar

Bryant is a Colorado Native who attended Mullen High School as well as being one of the original Slammers High School players. He played for Slammers in the Summer and Fall and earned a scholarship to Regis University as a pitcher. He played four seasons for Regis and was All Conference in the RMAC in 2010 posting a 1.88 E.R.A. in 40 innings. He was a Pre Season unanimous All Conference Pitcher in 2011.

He finished his career at Regis with the most games closed in school history and second in appearances. Bryant played independent baseball in New York, Chicago, Texas and New Mexico and was an All Star in 2012. Bryant coached at Mullen High School for three seasons. He was the Varsity Pitching Coach in 2012, Head coach of the JV team in 2013. Bryant joined Slammers in 2013 coached a Slammers Fall team. Bryant will coach a Slammers Select Youth team in 20147 as well as a Slammers Summer Select Team. he is also currently the GM at Slammers North.

Donny Kron

Donny has been head JV coach at Highlands Ranch High school. He played two seasons at Mendocino Community College in California. Donny also played at Panhandle State in Oklahoma and for the University of Alabama ( Huntsville ). He instructs baseball to players of all ages.

Yvette Hendrian

Yvette Pitched for the University of North Carolina from 1990-1994. She had the nations top 25 lowest era from 1993 to 1994. Yvette played in professional softball in 1998. Yvette was the assistant pitching coach for North Carolina for 3 years. She was the head varsity softball coach at Rangeview HS from 2008-2012 and then from 2012 to present at Eaglecrest. She was also nominated 2012/2013 Denver Post 5A Softball Coach of the Year.

John Quarton

John Quarton attended Metro State University from 1981-82 and then The University of Northern Colorado from 1983-85 where he played middle infield. He then went on to coach at Mullen High School from 1988-1998 and was Head coach from 1995-1998. He was the Head coach at Heritage High School 2002 to 2005. He has four final four appearances in the Colorado State 5A Baseball Championships. He coached in the state 5A championship in 2004. He currently coaches in Slammers Youth Select Program and in the Slammers High School Summer Select Program.

Earl Loseke

Earl Loseke has 19 years of Coaching experience. Earl has coached at the youth, High School and Collage Summer level. In the 19yrs, Earl has won 6 State youth titles and 1 National Title. Earl has one High School Summers League Title. Earl enjoys working with the youth, and teaching them not only baseball skills, but how to become great young men. Coach Loseke believes in hard work, and working hard today because tomorrow is not guaranteed.

Coach Loseke is currently a coach in our Slammers High School summer Select Program.

Levi Tapia

Levi Tapia was drafted in the 38th rd by the Boston Red Sox and was a 2005 graduate of Ralston Valley where he was a All-State catcher. He played three seasons of professional baseball.  Levi currently coaches in the Slammers High School Program and is one of our lead catching instructors. Levi also instructs on fielding and hitting.  

Mike Loseke

Mike Loseke played four years of college baseball at Otero Junior College and The University of Nebraska Kearney. Mike played independent ball for the Edinburgh Roadrunners. Mike has been doing clinics and working with the Select youth program for slammers for two years in the off season. Mike also instructed at the Kearney Little League for two years while in college.

Derek Colbert


Derek was born and raised in Lakewood Colorado. Derek graduated from Bear Creek High School in 2003 were he was a three time all conference selection in baseball. Derek continued to play baseball at Lamar Community College for two years were he was an all region selection as a pitcher his sophomore year. After Lamar Derek continued to play baseball at Metro State College and was an all conference selection his senior year as a pitcher. Derek graduated from Metro State in 2008 with a degree in Sports Industry and Operations and a minor in marketing. Derek has coached in the Select Fall Program, Summer Connie Mack and for the past four seasons has been a youth Select Coach.

Bob Smith

Graduate of East High School. Associate Scout Last 7 years Currently With New York Yankees. Previous with Cleveland and Atlanta. Head Coach for Rocky Mountain Baseball USA Junior Olympic Team Past & Years, Strength And conditioning With Cherry Creek High School. Select Team Coach Slammers Fall Program. Camp coordinator Arizona Total Baseball Winter Christmas Camp Past & years.

Jake Palmer


Originally from Montrose Colorado, moved to Denver to play Baseball at Metropolitan State College of Denver on a full ride scholarship as a catcher. Was a four year starter for metro as an outfielder. Finished up his career with many accolades such as 3-time all-conference outfielder, 2-time all-region outfielder, and a member of the 2008 Division 2 Rawlings All-American team.

Jake lead the nation in RBIs his senior year with 89. Finished his career with an overall BA. of .373 drove in 207 RBIs and hit 30 homeruns. Graduated from Metro with a major in Sports Industry Operations and a minor in management. Signed to play with the Evansville Otters of the Frontier Baseball League.

Josh Kiel

1st Team All Conference Catcher Bear Creek HS, CO 2001: Honorable mention as Jr in 2000 3 Years Varsity Baseball/ Football Attended: Orange Coast Community College – Costa Mesa, CA: 02 – RS – learned under John Altobelli Phoenix Community College – Phoenix, AZ: 03 – * 46% put-out/cs rate (attempting to steal 2nd) – played in an extremely difficult wood bat conference. Oral Roberts University – Tulsa, OK: 2004 & 2005 Earned Two Conference Championship rings while @ ORU as part of the Mid Continent Conference.

Participated in two NCAA -I Regional Championships Participated in One NCAA- Super Regional (Clemson’05) 2004 – set an NCAA record for highest team win percentage (50-11) *underwent shoulder surgery in summer of 04. Learned strategic drills/ techniques while under former USA pitching coach & current OSU pitching coach Rob Walton and current ORU head coach Ryan Folmar. I love baseball more and more each day and want to pass on the knowledge that was given to me so that players from Denver will have the same opportunities and skill sets as players from other “warm-weather” states.

Bryant Asnicar

Bryant is a Colorado Native who attended Mullen High School as well as being one of the original Slammers High School players. He played for Slammers in the Summer and Fall and earned a scholarship to Regis University as a pitcher. He played four seasons for Regis and was All Conference in the RMAC in 2010 posting a 1.88 E.R.A. in 40 innings. He was a Pre Season unanimous All Conference Pitcher in 2011.

He finished his career at Regis with the most games closed in school history and second in appearances. Bryant played independent baseball in New York, Chicago, Texas and New Mexico and was an All Star in 2012. Bryant coached at Mullen High School for three seasons. He was the Varsity Pitching Coach in 2012, Head coach of the JV team in 2013. Bryant joined Slammers in 2013 coached a Slammers Fall team. Bryant will coach a Slammers Select Youth team in 2014 as well as a Connie Mack Summer Team.

Marco Gonzalez

A native of Colorado and a four sport athlete at Wheat Ridge High School. Gonzalez went on to play collegiately at Oral Roberts University before signing with The St Louis Cardinals in 2006. Spent the next four seasons in the organization reaching AAA in 2009. Had a career year in ’08 going 9-1 with a 3.11 ERA between High A and AA. In four seasons with the Cardinals, Gonzalez has a record of 14-6 with a 3.48 ERA in 143 appearances. Gonzalez has spent the last two seasons as the closer for the Gary SouthShore Railcats in the American Association going 4-6 with a 2.45 ERA and 20 saves in 74 appearances.

Jake Jenkins

Jake Jenkins played for Slammers for 4 years and at Legend High School where he was All-State pitcher.  He earned a scholarship to play D1 baseball at the University of Pacific in the WCC Conference.

Jake was a four-year starting pitcher for the UoP Tigers earning All 1st Team Conference and runner-up pitcher of the year as a sophomore.  His junior and senior years Jake was All Conference Honorable Mention.

Jake Played summer collegiate baseball for Watertown Rams in the PG League, Mankato Moondogs in the Northwoods league, and the Brewster White Caps in the Cape Cod League.

Jake coached this past summer for our Slammers High School Summer Select Program and High School Fall Select.  Jake is currently the varsity pitching coach for Chaparral High School and instructor at Slammers.  He will be the head coach this summer for a Slammers Summer High School Summer Select 2020 grad team.

Jordyn McDonald
Jordyn played softball for Salt Lake Community College (SLCC) from 2008-2010 where she led her team to a #1 ranking in the country, and took 5th place at the NJCAA National Tournament both years. Jordyn had a variety of honors including 2nd Team All-Region (freshman year), Scenic West Athletic Conference Pitcher of the Year, NJCAA 1st Team All-American, NJCAA 1st Team All-Region, Louisville Slugger 1st Team All-Region, Louisville Slugger 2nd Team All-American, NJCAA 1st Team Academic All-Region and NJCAA 1st Team Academic All-American.

In fall of 2010, Jordyn transferred to University of California, Riverside (UCR) to complete her college career at the Division I level. Jordyn led their pitching staff in ERA, opposing batting average, wins, and strikeouts. Additionally, she ended her career with the 4th most wins and 5th most shutouts in their Division I history. During her senior year of college, Jordyn switched to the left side of the plate, becoming a sole slapper in the line-up.

Jordyn graduated from University of Denver with her master’s degree in Sport and Performance Psychology in 2016. During this time she was an assistant coach for the 18U Havoc. She is currently the assistant coach for 16U American Freedom – Balbin.
Brian Givens
Mike Fiscus

Mike Fiscus has been coaching and instructing baseball in Colorado for nearly 20 years. He has coached at various levels from 10 yr old competitive through graduated senior/college prep levels. He got his start on the High School side in the late ‘90’s at Fairview HS in Boulder, CO., coaching the Freshman and Sophomore teams and assisting with the JV and Varsity. In the summer he coached at the Legion C and B levels, assisting in a Legion B state championship during that time. In 2000, he moved to Parker and though not actively coaching with a school, he continued giving private instruction while fostering ambitions to someday get back to his passions of coaching. Beginning in 2009, he began to actively pursue being involved in the game, eventually gaining a position at Rock Canyon HS as a “C” team head coach. From there he was a Varsity Assistant at Heritage HS, which lead to Chaparral HS in 2014 where he currently remains. During the Summer and Fall he coaches competitive club for Slammers Baseball at the 16u-18u levels and gives private instruction year round. He currently lives in Parker with his very understanding and lovely wife, Amy, and his two daughters, Paige and Rachel.

Scott Bauer

Coach Bauer played at Highlands Ranch High School 1993-1997 where he was a catcher.  He later went on to play college baseball at Hastings College from 1997-2001 (Catcher, DH).

 He started coaching the Summer of 1997 right after high school at Highlands Ranch High School as the Head JV coach.  He coached over 10 summers and 4 springs at HRHS (JV and Varsity levels).  He later began coaching with John Cronican in 2003 for the Rocky Mountain Steel and eventually 5280 Baseball Club Teams.  Additionally, he spent one year as Assistant Varsity Coach at Arvada High School, two years as assistant Varsity Coach at Palmer Ridge High School, an then spent one season as a Pitching Coach at Mountain Vista High School.

 Coach Bauer started coaching at Slammers in the Summer of 2015 coaching the Graduated Seniors and continuing with Seniors during the fall.  He is currently a 14U Slammers Youth elect coach and Slammers Summer/Fall High School Select coach. He has over 29 years of coaching experience. Coach Bauer also is our catching and defensive coordinator at Slammers

Robbie Bales

Coach Bales enters his 2nd season with Mines Baseball serving as an Assistant Coach primarily working with infielders and hitters. Prior to joining the Orediggers, Bales was the Head Coach at Ralston Valley High School (Arvada CO.) where he lead the Mustangs to their best season since 2010 winning the 5A Jeffco League Tournament Championship. 

From 2010 to 2014 Bales was the Head Coach at Thomas Jefferson High School (Denver CO.) Where he piloted the Spartans to three Denver Prep League titles and was named Coach of the Year in 2011. While serving as Head Coach for TJ Bales  coached Colorado Rockies 1st round draft pick Kyle Freeland and Rawlings All-American Evan Walter, as well as All State pitcher and current Mines southpaw Sam Reed. Bales also coached the Colorado Instructional Summer program to the 2010 and 2012 Connie Mack State Titles.  

From 2006 to 2010 Bales served as the Recruiting Coordinator and Head Assistant Coach at Colorado Northwestern Community College, where he was the architect of three of the best recruiting classes in school history, and was recognized as the Scenic West Athletic Conference Assistant Coach of the year in 2007.  

Bales began his coaching career at Grand Junction High School and helped lead the Tigers to the 2005 CHSAA 5A State Title, while also running the Western Slope Golden Eagles fall and summer travel programs. 

Currently in the summer  Bales has been a part of the Mile High Collegiate Baseball League for five seasons, serving as Head Coach of the Denver Titans and Game Day Crusaders. 

Bales is a native of Magna Utah where he was selected as an All State shortstop at Hillcrest High School, He Went on to play at Colorado Northwestern CC and Cuesta College and was selected to the Scenic West all Sophomore team. He went on to sign as a free agent with the Anaheim Angels before injuries cut his career short.  Bales Currently resides in Westminster with his wife Anna and is a proud father of a son (Dillon) and two daughters (Taylor and Torre).

Josh Larrinaga
Conner Bitzer
Tony Wheeler
Chris McConnell

Chris is a New Jersey native where he was drafted out of high school in the 9th round by the Kansas City Royals in the 2004 MLB draft. He’s become a sought after infield and hitting coach with over 11 years’ experience as a personal instructor.