Bennett Whitmore had the opportunity to turn professional when drafted in both the 2008 and 2009 drafts (44th round and 32nd round respectively) but decided to finish his collegiate career at Concordia University before being selected in the 24th round of the 2010 draft by the Seattle Mariners organization. From there he started the 2010 season with the Rookie Pulaski Mariners of the Appalachian League and finished with the Everett AquaSox. In 13 games he compiled a 5.73 ERA and 19 strikeouts. Last year, Whitmore spent another season with the AquaSox where he posted a 4-6 record with a 5.40 ERA and 40 strikeouts while only allowing 13 free passes.
Spending his senior season at Concordia University, Whitmore also spent time at the University of Oregon (2008-09), Fresno City College (2007-08), and Fresno Pacific (2006-07). At Concordia, Whitmore finished his senior season with an 8-5 record and a 3.55 ERA in 15 starts. He led the team with 101.1 innings of work and struck out 98 batters holding opponents to a .263 avg.