The Rangers 2015 Pitcher of the Year, Tolleson was 6-4 with a 2.99 ERA and 35 saves in 73 relief appearances for the A.L. West Champs. He set a team record by converting 94.6% (35 of 37) of his save opportunities and tied for league lead with 21 saves on the road. Tolleson became Texas' closer on May 20 and went on to rank fifth in the American League in appearances and saves.
Tolleson is 12-6, 3.17 in 178 career relief appearances with the Dodgers (2012-13) and Rangers (2014-15).