Drew Bledsoe claims he didn't see it coming....
IMO, what Bledsoe didn't see was a revamped offense that would put more emphasis on a more agile QB (not necessarily mobile like Vick). If, as MM says, the offense will be adjusted, the adjustments will be with the QB coming in. With a QB like Losman, then even as a backup, Drew would be out of his element.
It may be that the new offense will employ more rollouts and require more athleticism from the Qb position, and rely less on a standard, drop back passer.
Losman affords us the possibility to be a drop back passer and also allows the offense to incorporate a more flexible, moving pocket. Due to the inconsistency of the O line, Losman may have a better chance of escaping when the pressure comes. We have seen time and time again that once the pressure is on, Bledsoe has tucked the ball and gone down. Losman has had a history of bad lines and being on the run through college. It is now up to Losman to take the step up to the pro game and become a leader at this level.