If you watch the game again, you’ll notice that on the previous series before the Welker incident, the Patriots did the exact same thing with Julian Edelman throwing a blatant shoulder into Dominique Cromartie-Rodgers, Denver’s best corner, that knocked him out of the game for a play.
What Belichick is crying about is that Welker took a tactic the Patriots use all the time and used it against him.
Is this what you were talking about?
I don't think that folks are complaining about the actual hit, just the fact that the ball had not yet gotten to the receiver, and it was an illegal pick. Guys hit other guys with shoulders all the time in football, and it is legal (like Edelman's). But not down field, while the ball is in the air, and picking the guy trying to play defense on the receiver.