What It Means:

Gallardo's rehab has progressed steadily through May, and if the simulated game goes smoothly he could begin a rehab assignment.

Despite a career-best 3.42 ERA in 2015, his 4.59 SIERA was the worst single-season mark of his career. His first four starts of this season were similarly concerning, and he posted a 7.00 ERA and 5.52 SIERA in 18 innings of work.