to keep him in the minors to fine tune it.

I'm a bit doubtful that pitching at 87 is good for him. Timmy doesn't use a 4 seam, but he still throws 94. I trust the Giants' staff with this though. They're excellent at developing pitching.

In any case, I think (or hope) that the cause of the velocity drop is a bit more complex than you're letting on.