Mike Deegan has served as the head baseball coach at Denison since 2013. Prior to coming to Denison, Deegan spent nine seasons on the Marietta coaching staff, helping guide the Pioneers to three NCAA Division III national championships (2006, 2011, 2012), six NCAA regional berths, and four Division III championship appearances. In nine seasons with Deegan on staff, Marietta won 30 or more games eight times, and they posted an overall record of 326-111 (.745).
Deegan served as the recruiting coordinator at Marietta and was the team's hitting instructor. In 2012 the Pioneers hit .331 as a team with a .414 on-base percentage. Marietta outscored its opponents 419-152 last season. In addition to his responsibilities with the baseball program, he served as a special assistant to the athletics director and was the Marietta Student-Athlete Advisory Committee advisor. Deegan spent 2007 serving as the head coach of the Southern Ohio Copperheads of the Great Lakes Summer Collegiate League. That season Deegan led the Copperheads to the most wins in franchise history (25), and the best postseason finish in franchise history. He was named the GLSCL Manager of the Year at the conclusion of the season.
A 2001 graduate of Marietta, Deegan was a two-time All-Ohio Athletic Conference first-team selection in 1999 and 2001. He was a major contributor on four OAC Championship teams, two NCAA Mideast Regional championships and two NCAA Division III Championship appearances. In his senior season, he started all 58 games, hit .393 with 46 RBI, seven home runs and a team-high 17 doubles. That season the Pioneers advanced to the national championship game. Prior to his graduation he was awarded the Way-Weigelt Award which goes to the top senior male student-athlete at Marietta. The award is based on scholarship, leadership, character and sportsmanship. Deegan received his bachelor's in management, and in 2006 he earned his master's degree in education from Marietta.