Bonzi Wells wouldn't be a horrible fit right now.
What does Bonzi Wells bring to the table that Tony Allen can't offer? A little more offensive versatility and better passing, although his long-range jumper is nothing to write home about. But that skill, while useful, is upset by Tony's superior defense. Bonzi has a bigger body (largely because he's overweighted), but I can't think of any NBA player I'd rather have him guarding than Tony. Maybe some guys who like to post up.
Most importantly, they both suffer from similar problems: inconsistency and thinking that they're better than they actually are. They both belong to the category of players Bobby Knight would rip apart. Last season Byron Scott was forced to stop playing Wells once things got serious in the play-offs because he never knew what could happen with him on the floor. That's precisely what I fear about having Tony as the first swingman from the bench.
Bonzi replacing Tony? It would make sense, but I think Tony is the superior player at this point of their careers and this is not factoring Bonzi off-court and locker room problems. Both of them together? Redundant, I think.