Problem with James Shields Mechanics?

Thanks to our friends at DRaysbay for putting this into my head. During yesterdays chat with Baseball Prospectus’s David Laurila, some concern regarding James Shields mechanics was raised. See Below:

Dennis (LA): Thanks for your great work. Your interview with Brian Bannister was one of the best things I read all year last year. Just wanted to ask you your opinion on two players: James Shields and Nick Swisher. What do you see in their futures and who do you think is the more valuable player?

David Laurila: Thanks, Dennis. Bannister makes any interviewer look good.

I recently had someone opine to me concern about Shields' mechanics, specifically that they haven't been consistent over the course of his career. Granted, that's not my opinion -- I'm only passing along what I heard -- but if true it poses a question.

Swisher can hit. Given a choice of the two, I'd take Swisher.

jlarsen (DRays Bay): Could Shields' changing mechanics be due to him regaining velocity and control post-surgeries(I think he's had one kind of reconstructive surgery already)?

David Laurila: This might be a good question for Doug Thorburn. I'll put it on the list, as it's better to get an expert opinion than my own.

I quickly took out the good ol’email address book and asked a pitching mechanics expert if he's seen anything in Shields that should be of concern. My source explained that Shields inconsistency is due to the fact that many different people have tried to get him to develop a “real breaking ball.” The source went on to mention that as long as Shields has a plus change up, he only needs a “show-me” breaking ball to be successful, and also that Jim Hickey is a great fit for Shields.