I know Frank looked good at the plate in his first game back in The Show, but he clearly was not in good enough physical condition to play if he already tweaked a hip flexor. In my opinion, the sox were playing well enough without Frank and they should have showed more patience with him, and demanded that he be in every-day game shape before they showed him some action.
Now, I just hope that this isn't a nagging injury that Frank could have avoided by getting more at bats in the no pressure enviroment of AAA. Frank's no spring chicken, and a few more sprints from first to third might have loosened him up a little more for when he really needs it, that is, with the Sox.
I think the Sox should have shown more patience and not listened to Frank's opinion that he "was ready". Clearly, he wasn't ready to spring around the bases when it counted, although his swing looked fine.
this being said, I'm rooting for me to be wrong and for frank to return tommorow pain free, and remain pain free all the way to the world series.