But they don't. What seems to happen is FB's tend to be covered by the worst of the coverage defensive players. WR's get CB's, TE's get a CB or a pass coverage LB usually. HB/FB's tend to get safeties or slower LB's. Not always but this seems common. And often times people even forget to cover the FB at all or put someone too slow to keep up.
So when you throw to players that do not have someone near them they will have a much better chance to catch the ball.
Also, as i pointed out, 4 of the 6 balls thrown to the FB in your game were screens, which means no one was around them to deflect the ball.
http://goallineblitz.com/game/replay.pl?game_id=1741111&pbp_id=6111007 This pass, he was uncovered and wide open.
http://goallineblitz.com/game/replay.pl?game_id=1741111&pbp_id=6109644 Here again, wide open, covered by a LB 10 yards away.
There is nothing inherently better about FB's catching passes. In fact it's somewhat surprising FB's get much action at all considering the generally poor play selections for them. Screens are easy to catch. Wide open passes are easy to catch. If you had a WR go out on a 5 yard route and was uncovered every time they would catch everything. Same with pretty much any position with more than 8 catching.