I think it is questionable at this point, actually.
His pass defense has gone from ranking #1 in passer rating against in 2009 to 31 this year: 1, 6, 3, 7, 20, 31.
His points against has gone from ranking #1 in 2009 to #25 this year: 1, 6, 20, 20, 19, 25.
His DVOA has gone from #1 in 2009 to #21 this year: 1, 5, 2, 9, 12, 21.
All of these stats have flaws, but there is clearly a trend there. I guess if he was a DC he wouldn't have to pay any attention to offense and special teams and media obligations and the like then maybe his defenses would be better, but he already basically pays no attention to offense and special teams.
He hasn't shown he can coach up a good defense without Revis, one of the greatest defensive players of all time.
His pass defense has gone from ranking #1 in passer rating against in 2009 to 31 this year: 1, 6, 3, 7, 20, 31.
His points against has gone from ranking #1 in 2009 to #25 this year: 1, 6, 20, 20, 19, 25.
His DVOA has gone from #1 in 2009 to #21 this year: 1, 5, 2, 9, 12, 21.
All of these stats have flaws, but there is clearly a trend there. I guess if he was a DC he wouldn't have to pay any attention to offense and special teams and media obligations and the like then maybe his defenses would be better, but he already basically pays no attention to offense and special teams.
He hasn't shown he can coach up a good defense without Revis, one of the greatest defensive players of all time.