As previously posted, something's not right with those quoted numbers. .125% is definitely drunk. But it's not passing-out-at-the-wheel drunk.
Several possibilities raise their heads:
1. He was really, really tired, and under the stress of the upcoming season, drank a bunch in a short time. The fatigue combined with the alcohol and put him over the edge. This is the story I expect from FSU.
2. The .125% measurement came a while after the arrest. His BAC was materially higher when he passed out at the wheel, but the Keystone Kops.....uuuummmmm...Tallahassee Police Department, waited as long as they could before administering the test. Given their treatment of rape by football players, that would be small potatoes. But they're under a microscope now, so I'd be surprised if they did that.
3. The BAC was accurate and timely. He was passed out to the point that the police had to wake him because of another substance. He was drunk and under the influence of something else. With absolutely no inside information whatsoever, this is where I'd put my money.