Bob Greiner was named Head Coach for the baseball team in the summer of 2009. He is the seventh head coach in the program's 37-year history.

In 2010, he led the Mavericks on a miracle run to finish the season, sweeping St. Thomas Aquinas in a five-game series to advance into the East Coast Conference Championships. It was Mercy's first post-season appearance in over 20 years.  His Mavericks compiled a 17-28 record in 2011, including a 10-20 mark in ECC play.

Greiner has a successful track record as a head coach, and now holds a 381-296 career mark in 15 seasons including stints at Manhattanville for two years and Concordia (N.Y.) for 11 years. During his tenure with the Clippers his teams made nine playoff appearances, captured three New York Collegiate Athletic Conference (NYCAC) championships (1999, 2000, 2002) and earned four NCAA Division II Regional bids, advancing to a pair of finals.

Greiner is known for his recruiting and player development skills that have led to numerous All-Conference selections and seven All-Americans, including 2003 Division II National Player of the Year Mike Aviles, now with the Kansas City Royals.  He has had four players drafted and gone on to play in the professional ranks.

Greiner was voted by his peers as the 2002 NYCAC Coach of the Year after guiding his team to a 44-12-1 mark, which was a New York State record. He has also served two terms on the NCAA Northeast Regional Advisory Committee.