Team needs another mammoth DT like Wilfork. Brown isn't it, he I see as always being a #2 DT. Branch was it for awhile but has seemed to regressed.
A big DT who takes up space and occupies a center and a guard opens up lanes for LBs, blitzes by DBs and enables DLs to get to the QB. Team needs a DT like that as well as fresh legs on DB, LB and DL
Offense I would invest in a QB, TE and OL.
I agree with DT. Brown is a good player in a 4-3, but not a 3-4. They really could use another athletic Wilfork type, or just a big huge Ted Washington blob type (and I say that with the utmost respect).
LB was a cause for concern going into the season, and it didn't get any better, though they have Rivers coming back, and he's more of a OLB/DE hybrid than a pure DE IMO. I could see them re-signing Harrison if he wants to continue, and using him 20 snaps a game.
I actually think their OL depth is good, but it hinges on what Solder decides to do. If he retires, I'm not sure what they do for LT.
Cannon struggled this year, but was dealing with an injury and was excellent last year. Mason was great, and unfortunately had one bad play in the SB that led to the Brady fumble. Andrews is good, Thuney is ok, but got better as the year progressed.
Definitely think they need to invest in a QB as well in the draft.