Deep throws are low completion percentage passes even with great QBs. You're going to waste a lot of plays throwing deep with Hooker. If he's the starter, then you can count on the offense leaning on running the ball and not his arm. Milton is a mystery right now, other than his physical talent. Maurer is physically talented but has been very inconsistent. The most consistent passer that was put on the field last season and in the spring game was Bailey. He's accurate and has plenty of arm strength. He's not a runner, but he wasn't a statue last season either.
Tennessee has suffered on offense for so many years because of poor QB play and a mostly ineffective passing attack. The o-line has played a part at times, but it really comes down to the QB. You can also look at Heupel's offenses in the past and it's clear that putting up a lot of yards through the air is important. We need the QB that can get the most out of the passing game. I think that might be Bailey, but we'll see. Maurer and Milton are more than capable. I really think Hooker is just good insurance on the bench if the other guys fail or get hurt.