He hasn't, actually. He's getting tackle numbers like Monty Beisel / Gary Guyton 2.0.
The best way to probably see this is look up highlight videos not of the pats, but look at the week1 Dolphins highlight video, week2 Jets video, week3 Saints video. Bentley misses guys all over the place and takes bad angles.
Why do you think his snap count keeps going lower and lower every game? I'm glad Van Noy is back and him plus Hightower are slowly getting their legs back. But just go get Collins, that gives the team 4 vets plus Uche, then go find a big fat NT to fix the defensive line.