Was Bo supposed to be Johnny Manziel?

They are both million dollar arms with five-cent heads. But I doubt Hollywood is that smart.

no russel wilson.. he is the seattle qb and he played college at wisconsin

No - the movie was clearly plotted out and written long before anyone knew much about Manziel. Callahan was just based on a general type. Sometimes life imitates art.

To the extent there's any contact between the specifics of the world of the movie and the real world, they're mostly backwards (Seahawks have #1 pick when they just won the Super Bowl, Wisconsin quarterback is a "sure" #1 with character problems rather than a third-rounder with character virtues, etc.) - which makes it clear they were working with real team names, but in an abstract world, likely years before the movie was made.

Not at all. Bo is supposed to be the prototype NFL QB, but with hidden problems. Manziel is a heralded college QB who many thought lacked the size and ability to stay in the pocket that an NFL QB needs and who's problems were all too well known by everyone. Bo appears to be based on draft bust Ryan Leaf, who was even mentioned in the movie.

If there was a pro QB who Bo's character was based on, my guess is it would be Ryan Leaf, even though Leaf didn't go #1. Still though, heading into that draft the general consensus was it was a "pick 'em" between him and Peyton Manning as to who would be the better QB. Leaf was huge, with a big arm, and fit the "mold" perfectly of what the classic dropback QB is supposed to look like. But he was also a jerk, and didn't have the mental toughness to catch up to the pro game once he started getting hit by NFL linemen and linebackers every game.