So, we still haven't seen much of Frank's background. Lost has been tricky with these kinds of things. Sometimes, we never get to see a characters background, like Libby. Other times, as in the case of Charlotte, we are shown the character's story in a different context, indirectly. For instance, we never got a look into llana's past. However, this could easily be shown to us from Jacob's point of view.
Then there's the Lost habit of killing characters in their centric episode. Is it possible that we will get a glance at Frank's background, then he will be killed at the end of the episode? This could possibly be justified with the mysterious outrigger chase from season 5. Maybe Frank will be shot and killed by the time jumping losties. This might be hard because the flash-sideways and original timeline stories are gaining momentum.
Maybe we will never see a Frank centric episode, and everything was resolved when he simply stated that he overslept, and missed Flight 815.
Just a few thoughts.