Spread offense in the NFL is based on the QB knowing the defensive package and the WR's being on the same page, this changes what routes they would run according to what package they see. This is a very difficult offense to run with a real good QB let alone a rookie who basically played in a "run and gun" offense. College football is more about the better athletes on the team then the offenses being run. All NFL teams have great athletes and it comes down to prep work and execution.
You say plenty of rookie QB's have done well but majority of them are protected by a run game that is dominant and a equally dominant defense (usually) i.e. Big Ben, M.Ryan who struggled badly when Turner rushed for less then 100 yards, Flacco who's numbers we're nothing special.
M.Leinart came from a pro style offense and has the two best WR's in the game and has struggled to get it.
NFL defenses will disguise defenses and contain White to the pocket as best as they can and let all 6'0 of him throw the ball. Of course he'll escape here and there but in the long run he will struggle to move the ball. A spread offense doesn't allow the QB to hide behind a strong run game and play action your way to easier throwing lanes.
BP and TS stress being conservative with the ball, no turnovers, punt for field position and force teams into mistakes. What part of the spread offense to you is conservative when it comes to turning the ball over. We won games because we never turned the ball over, played sound defense and had to rely on a wildcat run game due to injuries. But now all of a sudden because the great P.White is here we will abandon this to run some spread offense that is high risk, high reward. That doesn't seem to make sense unless we have developed this brand new spread offense that is highly conservative and if so why not just pound the ball and let Penny do his thing?
I must be missing something, especially the part about the rookie Qb coming in and putting the fear in defenses with pass or run threat. And I thought all those championships that M.Vick won we're in dog fights not superbowls.