IF we were to somehow get the #1 pick for Jimmy G we would have to trade down for a couple of reasons. The first being as freaky athletic and talented as Myles Garrett is, he is not a sure thing and has some bust potential. Using all of that potential value on a single player would be a huge risk and would always be compared to the success of Jimmy G. I see BB trading down for additional picks and spreading out that risk so it isn't Jimmy G for a single player.
The other reason I think we would almost certainly trade down is because of the way the Pats view pass rushers. I remember watching Michael Lombardi after the Chandler Jones trade talk about why the Pats made the move and how they value pass rushers differently than the rest of the league. He said the Pats don't care about sack numbers because they ask so much more out of their edge guys. They value things that don't show up on the stat sheet which means they value players differently to the rest of the league. We also use a more rotational approach to keep guys fresh and give different looks which also devalues individual players. Because of this, although I think they may love Myles Garrett as a player, they wouldn't value him more than the value they could get trading out of the #1 pick.
I agree with
@manxman2601 that BB would love Jamal Adams. He and Reuben Foster are the two guys at the very top of the draft I think would be best fits. We know how much Belichick loved Sean Taylor coming out of Miami and he is one of the players that Adams is most often compared to. A big, physical and athletic safety that can run, hit and cover would add a lot to any defense. I find it difficult to see a scenario where we could trade down and still get him because I think he will go very high, but I would have no problem drafting him. In the end I would be happy with one or more trades down that could net us a future 1st and a few extra picks this year. The multiple trades back
@BobDigital posted would be perfect.