re: Main reason I want Sims to be the guy:

In addition to the one he sailed high, Coker missed on a few other short ones. Off the top of my head, he badly missed Fowler, missed TFS (May have been due to wet ball), and one of his screens to Cooper was completed but was very low which messed up the play.

I wouldn't say the short throws are particularly hard but they are very important in the WCO and Sims has been near perfect on them which isn't something that should be discounted. Missing just one of those throws puts the O behind the chains which is another reason why Sims hasn't needed to make long throws thus far.