The roster is garbage. Going to Zappe earlier might not have changed anything. Maybe they lose the games they lost with him under center. Maybe they don't. It's impossible to say. I mean, the teams Zappe has beaten haven't been the greatest. The Broncos are a middling team (how many 3 and outs did the Pats have?), the Steelers are a below average team. Zappe was shut out by one of the worst passing D's in the league (at home no less).
People wanted to talk about a "signature win" with Mac. Zappe hasn't had one either. Let's see him go up against a legit contender and see how he does. Buffalo is playing for their playoff lives so we'll see how he does next Sunday...but even they're trending in the wrong direction.