It's pretty simple. Lex Hilliard is about as useful as a migraine and Bohannon isn't exactly going to be up in arms not having the starting job his rookie year after being a 7th round choice. We probably won't have any receivers of note (even if Holmes returns, he'll almost definitely have lost a step), a questionable offensive line that's prone to injuries, a QB that's either a rookie or a buttfumbler, and a running game with a lot of potential but very little hard evidence to go by. In other words, our offense right now is a joke.
Adding a fullback like Leach, who definitely has at least another year or two of high caliber performance left, will give us a PROVEN player at the top of his position on our offense. Right now, we only have two of those, both of which are on the offensive line, one of whom has some injury history and the other of which lost a step last year. Leach can take a ton of pressure off of whichever QB we go with and he can add veteran leadership, which is never a bad thing. He should be cheap and has a great resume. I say, get him, because he might end up being the best player on the offense. Which is sad, but hey, that's where we're at.