Slammers Baseball is the Premier Baseball Program in the state and region with some of the finest indoor training facilities.

Slammers is dedicated to fulfilling the needs of players of all ages and abilities. Our staff and instructors have over 70 years of combined High School, College and professional playing and coaching experience. We offer a wide variety of instruction including private one-on-one lessons, group and team clinics as well as specialty camps offered throughout the year.

We also have youth leagues and competitive youth and High School travel teams. We have placed hundreds of players in every level of collegiate baseball and the Major Leagues. Regardless of your skill level, you will benefit from our staff’s vast knowledge of pitching and hitting and fielding. Our 22,000 square foot Englewood facility offers 11 indoor tunnels for personal or team rental and size fully automated pitching machines to refine your baseball and softball skills.

MEET THE SLAMMERS TEAM

Clint, Billy, and Mark are widely recognized as some of the best instructors in the region. They are highly sought after and are credited with turning out some of the best pitchers and hitters in Colorado. 

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 J.K. 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 8000 private lessons. Mark has coached from the ages of 6 to High School. He has competed with the Slammers teams in National tournaments across the country. Mark is currently an associate Scout for the Kansas City Royals.

BILLY MARTIN

Billy played 4 years at the University of Texas at Arlington and was then drafted in the 34th round by the New York Mets. Billy was 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 3 time minor league all-star with a career .285 batting average and 94 home runs.

He played 8 years professionally at 4 positions (1b, 3b, lf, rf). Billy is now part owner and a full time instructor at Slammers since 2005. Billy specializes in hitting, fielding, and throwing at all levels; he also works with youth pitchers. Billy has a Bachelor’s degree in kinesiology from the University of Texas at Arlington and a MBA from Denver University. Billy is also a Certified National Strength and Conditioning (NSCA) personal trainer. Billy is 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.