I must have missed something. IMO, of all the aspects of the 2019 patriots that needs improvement, it is the pass defense that needs the least improvement.
It seems that every year, we add the normal number of new players on defense. And every year, several posters want to change our defense because the league has changed. More than anything else in his coaching and GM duties, it is here that I trust Belichick the most. He may the very best (or close) in the league at developing and adapting defenses. Of course, it is frustrating to see the early games, since part of the Defense According To Belichick is for the defense to develop as the season goes on with the idea the the defense doesn't really gel until mid-season.
Yes, we do need to adapt to the losses of KVN and Collins. Winovich will pick up some of the slack, as will our rookies Uche and Jennings.
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I look to new schemes that will help in our RUN defense. At times, it seemed to be weak, especially against option and running quarterbacks, a problem for many years.
Perhaps, Bentley and Cowart will step up. Maybe we'll play Onwenu at NT. Perhaps Allen will be better than we think.
IMO, the current defense would be helped most by the addition of a DT. But then, I said that before last season, and Belichick disagreed.