I also am not worried about the front seven. I agree that an additional DE/OLB upgrade would be good. I'm not sure that Belichick will see the need. Of course, he will bring in one if the value is there.
Re-signing Carter and Anderson would be a fine start. I would also want to re-sign White.
DL: Carter, Wilfork, Love, Deaderick
LB: Mayo, Spikes, Ninkovich
Situational: Anderson, White
Backups: Fletcher, Pryor, Cunningham
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We also have Tarpinian, Niko, and Markel Carter.
BTW, I think Ellis has been effective against the run. Obviously, he isn't worth his current salary. Also, G. Warren could be back as an emergency backup and/or camp insurance.
Which makes it hard for the likes of me to know what we need
Regardless, Mayo, Spikes, Nink, Wilfork should be solid starters next year regardless. If we were to re-sign Carter that's 5 out of a starting front seven.
Deaderick, Love and a possible re-signing of Anderson would fill most of it out. I think we mostly need a pass rusher whether we call him a DE or OLB.