Elbow on purpose? I am sure of it.
Haven't seen much worse? Then there is no way you watch much football. Brady gets hit worse than that at least 3-4 times a season. I see plays that are that bad every single weekend. The only difference is
a) A QB got injured.
b) NE was involved.
Last year, for example, Kyle Vandon Bosch literally dove into Brady's front knee without any OL around him. It was a clear and blatant attempt to injure a player that stood in the way of TN making the playoffs. They also attempted to injure Ty Warren and Rodney (successful with that one). Brady also has speared in the kidney as he was sliding by a Jax player who lowered his head to ensure maximum injury potential.
Wilfork was essentially tackled by the OL and stuck his elbow out to try and disrupt the play. Nothing more, nothing less.