I can't find the link now, but someone tweeted yesterday that AA says that Stroman and Sanchez have an innings limit of 180 (rather than the <140 speculated before)
I'm too lazy to look up the MILB+MLB figures now, but I guess if you looked you can gauge where both would end up (don't forget probably 3-4 post season starts as well)
As for who, I think it's clearly Hutchison. Happ hasn't done anything lately to deserve a demotion. Hutch could use a breather in the minors