Mickey O'Brien came to work for General (then Major) Bob Neyland in 1938, just in time to ride three back-to-back unbeaten and untied seasons to successive bowl trips. Mickey, in his own quiet way, became almost as legendary a figure in UT football history as the man who hired him. He served as a jack-of-all-trades for the Vol program. In addition to being head trainer, he also served as head trainer of all sports teams, was in charge of Varsity Inn (the training table), oversaw the equipment and laundry operations, and served as chief recruiter in Chattanooga, North Carolina and Florida.

Mickey blazed a lot of trails in his time. Many of his designs and innovations in playing equipment (bolstered hip and shoulder pads), first used at UT, were universally adopted. Experts in sports medicine regarded O'Brien as one of the premier college trainers of all time. A member of the Helms Foundation Hall of Fame (now called Citizens Savings Athletic Foundation Hall of Fame), he helped form the Southeastern Conference Trainers Association and was it's first president. He also was an officer of the National Trainers Association and is an inductee of the Tennessee Sports Hall of Fame.

UT named an award for Mickey O'Brien in 1967 which has been given annually ever since, to the senior player who best exemplifies courage and determination to overcome physical obstacles during his career and make a valuable contribution to the team.