Some stats from Mazz:
"So far, through 17 starts, Sale has thrown 138 fewer pitches and totaled 11.2 fewer innings than he did a year ago. Given that Sale is precisely halfway through his season, that translates into a commendable savings of roughly 276 pitches and 23.1 innings, essentially the equivalent of three starts."
Mazz also points out that Sale started to fade in August last year, so he may need even more rest in the 2nd half of the season. I'm not sure if that will be possible, however, given the tight division race with the Yankees.