My bad - here I thought the 52 games his missed this year with a finger contusion (when he got his finger caught in a falling suitcase) would have qualified under "finger stuff" or "finger issues". I'd image the pain, flexibility, strength, etc. from that could impact his velocity.
BTW - is there any game by game spin rate stats available to see whether Sanchez has a decreased spin rate since returning from the blister issues?