First off, quarterbacks are excluded to make things more interesting. It goes without saying, for example, that Marcus Mariota is Oregon's most important player.
And most important doesn't necessarily have to be "best." An All-American's backup can be pretty darn good, too. USC's Leonard Williams might be the best defensive lineman in the nation, but is he the Trojans' most important player considering the talent and depth on their D-line?
Our most important guys are players who could swing a win total one way or the other, based on their living up to expectations. Or their absence.
Brennan Scarlett missed the 2013 season with a hand injury.
Why Scarlett is so important: California had the worst defense in the Pac-12 last year. In fact, it probably had the worst defense in school history.
The Golden Bears yielded 45.9 points per game. They also ranked last in the conference in total defense, pass defense, pass defense efficiency, opponent third-down conversion percentage, red-zone defense, fourth-down defense, etc.
Part -- perhaps even most -- of the reason it cratered so badly was injuries. Scarlett was arguably first among the long list of key players missing all or significant parts of the season, as a hand injury developed a staph infection and spiraled from there, forcing him to miss every game and even, for a worrisome period, threatening his career.
In 2012, he started nine games and registered 40 tackles, six tackles for loss and 2.5 sacks. He flashed tremendous potential, and the general feeling among his coaches hasn't wavered: A healthy Scarlett should become an NFL player.
The Bears desperately need him to become a pass-rushing threat. While questionable everywhere, the Bears secondary has the most issues, so it can't afford to be exposed to a quarterback's eager eyeballing for five or six seconds every pass play. Last year, Cal had just 18 sacks. If Scarlett plays to his potential, the 6-foot-4, 265-pounder should at least approach half that total on his own this fall.
If Cal is going to have a bounce-back season, its defense must improve dramatically. It is difficult to believe that would happen without Scarlett becoming a disruptive force.