this is correct. also, look at the push those lines do (or don't) get in the run game. i think it's save to say that right now we have a weaker line than any of those teams.
for the record, i think trent is better than fitz in every way except that he has something making him horrible tennetive. after he recovers he should look to the pressue caused by fitz and start. i say this of course with the caveat that if fittz plays objectively well (like 250+yards, 60%+, 7+ per attempt, Tds and few INTs) then he stays. if trent comes back and is too trigger shy to score, well we still have fitz to jump in.
IMO that's how you handle a qb issue, apply pressure to play well, not to win some starters job (and thusly excusing bad play down the line, sort of what has happend wtih trent).