NFL Network had some film breakdown on Moss tonight showing some of the ways to use him. A few of the plays were just him beating guys one-on-one, or even catching deep balls that shouldn't have been thrown to him because of double coverage.
The really interesting stuff was Moss lined up in the slot or in motion forcing a matchup against a nickle corner or linebacker who had absolutely no prayer of covering him on a slant pattern. This left Moss singled up against a deep centerfielder safety....a total mismatch.
Can you imagine the poor nickle corner trying to cover Moss on one play, Welker on the next? With Moss, it's everything you can do to keep behind him. With Welker, it's impossible to stay tight with his cuts.
I think the reason Belichick knows things will be fine with Moss is that Moss understands how defenses try to stop him and will enjoy the games that Belichick plays to make those defenses pay.