basically they have too many starters to fit in a rotation and all of them are either established guys with big contracts that it's hard to picture in the pen (maeda, ryu, mccarthy, rich hill), young guys who are pitching better than the old established guys (urias, alex wood), or kershaw (kershaw)
so basically what they've been doing is coming up with very conveniently timed and iffy-sounding "injuries" for the veteran guys. mccarthy supposedly tweaked his shoulder (non-throwing, luckily!) in a "weight room incident"... maeda came up with "hamstring tightness" a day after pitching into the 9th... ryu felt something... somewhere... all three of them have missed exactly one start and come back fit as a fiddle and ready to pitch precisely on the 10th day, the team having meanwhile enjoyed the additional pen arm (or, more to the point, not had to demote any High-Status Veterans to the bullpen) for the intervening 9 days. everybody gets more rest... it's really not a bad system, as long as the league office keeps their big nose out of it
nice thing is, everybody's at least a little bit injured all the time (i know i am), so, on some level it's hard to argue with