The Patriots have one of the best defensive tackles in the league in Vince Wilfork, but they have made a notable effort to bring in someone to help him out this offseason. First, it was the signing of CFL defensive linemen Armond Armstead. On Monday, the Patriots reportedly signed former Raiders defensive tackle Tommy Kelly to a two-year deal. The competition is heating up headed into the offseason, and the defensive tackle position could be the latest example of the volume approach which we highlighted on Going Deep a few days ago. Here's a quick reset on the Patriots battle for playing time at defensive tackle.