4. The Sooner defense has been solid.
Oklahoma's defense has really played well for the most part this season. Even in the Sooners' embarrassing loss at Baylor, the defense held strong early, and only fell apart after it continued to get no help from its offense.
The Sooners are 23rd in the nation in scoring defense, and 13th in total defense. If OU's offense can do its part and avoid three-and-outs, it's not unreasonable to think the defense could have some success against Alabama.
5. The chip on OU's collective shoulder.
For as much as Stoops, his staff and his players insist they don't pay attention to what's said and written about them, it's obvious that they're at least aware of the overall perception of the program: The talent is down; the program is in decline; OU isn't near the level of the Alabamas and Auburns of the world; etc.
The Crimson Tide really don't have much to prove in the Sugar Bowl — three out of the last four national titles says everything you need to know about the state of their program — but the Sooners have everything to play for and lots to prove.
We've seen time and time again that in football, a team can be greatly overmatched physically, but still find a way to prevail. Oklahoma faces long odds and a steep, uphill battle against Alabama, but an embarrassing loss is in no way a foregone conclusion.