And with Martz recently claiming that it's a true 3-headed competition with JT in the mix, it really seems up for grabs. Here's how I see it:

(1) Alex will not be 100% this season. At the very least, his arm will wear down and lose strength as he throws with more velocity and gets hit in games. Physically, he might look good initially (maybe even impressive), but will have endurance issues as the season wears on. He had forearm soreness last season, and I suspect it was due to over-compensating for his lack of shoulder strength. This could be a recurring problem.

(2) Shaun Hill played well in the familiar West-Coast offense last year (short quick passes, spread the ball around), which was his comfort zone after practicing in it for several years. But how will he transition to Martz's offense? My gut feeling says Shaun's limitations will quickly be exposed in a new style of offense. Although Martz's offense doesn't need a strong-armed QB, Shaun's arm strength seems far below NFL average. Shaun is tailor-made for the West-Coast offense, and might have trouble maintaining his accuracy on intermediate/deeper throws. However, if I'm wrong and his arm strength is stronger than I've seen, then he will be the starting QB this season.

(3) All reports indicate that O'Sullivan has good enough arm strength and the accuracy to be successful, but I'll have to see it to believe it. My guess is that his upside is limited due to his consistency and decision-making. A guy with his (supposed) physical tools must be a horrible decision-maker to be stuck as a career backup for 6 years. I suspect he'll have a fast start in mini-camps but fall to the 3rd QB spot after a few scrimmages.