One of the differences I've heard about relief vs starting is that relievers can let it all hang out since they'll only go an inning or two if that.
This seems to be the case with Myers. Watching him pitch he was almost leaving his feet on his follow through. Not the pitching style he used to use when starting. He always had a good fastball, but I don't recall him ever hitting 97 like he did the other night.
IMO its possible he may have been going at it a bit too hard trying to get even more out of the pitch then he had to give.