Normally it's disappointing when a player is sent to the minor leagues, but in the case of Max Scherzer this may be a positive development. Scherzer has shown many signs that he could be injured, and the fact that the Diamondbacks are on record as trading him due to concerns about his durability only fuel those worries. His velocity has dropped, and he has been very easy to hit, both things that make you wonder about a guy who we are used to seeing blow it by the opposition.
A demotion rather than a trip to get a medical scan or to the disabled list makes me think that this is a mechanical issue more so than a health one, which means this is, potentially, a temporary stumbling block for those who have not given up on Scherzer yet. Scherzer noticed a mechanical problem on his own after studying video of his beat down against the Red Sox, when he allowed five first run innings including a home run to David Ortiz. His arm slot was lower than it had been in Arizona, and his pitches have been coming in too flat because of it.
This has hurt Scherzer in many ways—hitters are making more contact against his pitches, and better contact. His fastball has been worth -10.4 runs already this year, thanks in part to the opposition making contact 83 percent of the time rather than last year's 77 percent, but the fact the ball has left the park nine times already this year (20 in 2009) hasn't helped either.
Correcting his arm slot and recovering that downward plane for his pitches could go a long ways towards Scherzer recouping value in your league. There's no timetable as of yet for his return, but chances are good that if he can make progress on his mechanics then he'll be back up soon. In mixed leagues you may be able to get away with dropping him (if you haven't already) but in deeper leagues, you may want to just stash him on the bench for now and hope he isn't gone for too long. Scherzer has immense value as a starting pitcher if he can get his stuff back to where it was just last season, as this was supposed to be a pitcher on the rise.
One more thing to remember: Scherzer's ERA is 7.29, but his SIERA is 4.92. Even with his struggles, he was nowhere near as awful as his ERA suggested, and if he is promoted again and has his arm slot in order, both the ERA and his SIERA are going to drop back to the levels we expected him to be at when the year began.