So I re-watched the game last week. Browning clearly struggled, as the game wore on, with pressure and accuracy. But I still can't agree with @Dennis_DeYoung's "choked" assessment.
Going from memory here...Browning started the game something like 10-12. Not fazed by the moment or the (extremely loud, intimidating) Ga Dome atmosphere, he came out sharp in Q1. And the offensive gameplan was working early. When Ross fumbled, UW was driving again, with a very promising looking chance at a second score. That fumble was a gut punch, as everybody knew UW needed to be +2 (minimum) on TO margin to have any realistic shot at an upset.
By Q2, Bammer's defense made good adjustments to the motion, misdirection, and screens that were working early. As soon as they figured out what UW was doing, the athletic superiority of their D came to the fore, and there just wasn't anything Browning could do. At the moment Jake threw the pick-six, he was still something like 12-18.
UW couldn't run, despite continuing to earnestly try. UW couldn't protect the pocket. And Bammer's secondary had UW's receivers completely blanketed downfield. This was more apparent in the stadium than on TV: The pass rush was overwhelming, it was louder than fucking bombs, and there just weren't any open passing targets. Ross was consistently doubleteamed. Because Browning wasn't born to make plays with his feet, Bammer's D (for the final three quarters) was basically able to confine him to his first read on every play, which really takes away one of Browning's greatest strengths as a QB.
DdY called Browning's problem "mental." I can see why. As the game wore on, Browning got battered and frustrated. The optics weren't good on TV. Time and again, you could read the frustration on his face after the play. Composure under duress is something Jake definitely needs to work on, in order to take the next step as a team leader. This is something the staff should emphasize in the film room with him, as I do think it's fixable. I doubt he's ever gonna be Saint Marques, but he can lead by example much better.
At the end of the day, though, UW didn't lose because Browning "choked." All the mental toughness in the world wasn't going to change the outcome of that game. Jake made one disastrous decision on the pick-six, and he missed on a lot of other balls. But I just doubt any collegiate pocket passer (pick one -- Luck? Brees? Peyton?) could have won that game for UW, given the TO margin, the blanket coverage, and the lack of protection he was facing.