My commentary from the Scherzer diary:
Regardless, I think the GIF shows that Webb starts wonderfully by dropping his pitching hand and elbow very low out of the glove, and despite what the poster on BTF thinks, his early break out of the glove is a good thing.
However, once Webb starts cocking for delivery, things go a little haywire. His body, which had been in a downward trajectory towards home plate, starts to stand back up and he starts to raise his elbows into that "upside-down W" position.
He follows that with a nice flare of the hips, which cause his shoulders to follow around. His front foot comes around to a good landing position. He doesn't land on his heel, but on the whole foot.
It's hard to tell for sure at this angle, but it seems to me that his elbow is high when it comes around for delivery. It also appears to me that Brandon starts to pronate his upper arm, which isn't good. However, it does look to me like he has very nice weight transfer to his front foot and his back foot slides off the rubber nicely.
I emailed Chris O'Leary last night... it'll be interesting if he responds. In my extremely un-educated opinion (which, let's face it, O'Leary's opinion is more studied, but just as un-educated) I'd say that Webb does almost everything right, but the upside-down W and early pronation could be putting stress on his shoulder and elbow."
I asked and I received: Chris O'Leary blogs about Brandon Webb's mechanics.
He comes to the conclusions I thought he might, but adds that he locks his glove-side knee on follow-through, which could raise the chance of hip and knee problems.