This is an interesting scenario to me.
Clearly there is no future (and depending on how much stock you put into his time with TB last year, no present) with Josh McCown as the QB of the Browns. Given his age and the fact that minus one 6 week stretch with Chicago he's never really been that good to begin with. That's pretty obvious to anyone who watches or understands football.
That said, it's certainly possible/likely that based on what we - and more important, Pettine and his crew - know of and have seen so far that Johnny Manziel is actually WORSE than McCown.
Regardless, common sense says give Manziel every rep, every snap and let him sink or swim. He'll almost certainly sink, but at least you'd know beyond a shadow of a doubt that he can't play plus you'd be in a position to land whoever the top QB is next season. If by some miracle he doesn't sink, then maybe you have something moving forward. But pretty much every person on this board knows before this season even stars that the Browns are going nowhere with McCown.
However, since the Browns won 7 games last year, I think it is certainly plausible that ole Jimbo Haslam is dumb enough to not understand that record was the byproduct of A. an EXTREMELY weak schedule and B. a string of a good fortune with not turning the ball over the first half of the season.
I think Pettine realizes what he's dealing with ownership wise and is going to do whatever it takes to squeeze out as many wins as he possibly can this year in an effort to keep his job. If they were to play Manziel all 16 games, he fell on his face, and they were to go 2-14, Pettine would assuredly be fired, fair or unfair. If they play McCown all 16 and go 6-10, perhaps Pettine isn't fired. I absolutely think Jimmy is stupid enough to use last year's 7 wins as a bench mark without using any context behind that number.