Yes. Mallett is entering only his second full training camp. He has rare talent in throwing the football, and "needed maturity" in the year he was drafted. Father time has added three physical years and he is obviously less of a kid.
Plus his athletic drawbacks have yielded to good coaching. His footwork is much better now, and has greatly reduced the sailing passes he used to throw, because his arm was so strong. He knows the Playbook, and needs reps, and increased final accuracy. Under coaching, he his being trained to have some "touch"on very short attempts, but that has not yet been mastered, yet. Still the improvement is evident. I know Belichick spent 4 preseasons grooming Matt Cassell before he thought Matt was ready.
Mallett is way ahead of that schedule, and could probably already do a "Matt Cassell" reprise this season; but I think he won't be fully groomed without playing, until the end of NEXT preseason.
As far as your boy is concerned, Tim should go to Canada for three or four years. Joe Kapp couldn't pass either, yet he won Grey Cups before coming to the NFL and getting the Vikes to a SB appearance.