This is the key. I had trouble going deep using the Pats with Brady and Moss until I discovered this. The ball would hang in the air and the DB would always catch up. This hits the wideout in stride.
I've found this works best around mid-field. If you have a good wideout on single coverage running a fly pattern, you can get a lot of long TD's this way. In one game against the A.I. I had over 300 yards receiving with Moss, with 3 TD's of 50-60 yards. This was with the difficulty on pass offense turned up to 17 (although it was against the Chiefs, who don't exactly have a ton of talent at DB.. or any other position, for that matter.)
If you have the talent on your team, you can ravage a defense with the long ball, if you use it properly.