A questionable metonymy, perhaps, but I think it works, that the Miami players were not actual convicts but the word conjures them because of stereotypes.
It’s nice too that in the beginning of the article at bottom there are competing metonymys: Beijing v. Washington.
One of those classics metondoches (should I add this to the portmanteaux list…?) that could go either way. As a metonymy, the bat of course suggests the power behind it, if not the batter himself. As a synecdoche, the bat is a part of the batter. If I were forced to choose, I would say that metonymy is the stronger interpretation, but either one works. What do you think?