Both Duggar and Onwenu are good, not great players.
Onwenu might not be a great fit for the AVP more mobile OL scheme. Onwenu was the tackle on the #32 OL in the NFL, and is big and stout. AVP plays a more athletic approach. Onwenu is a better guard than tackle. The Pats have Strange, who, on paper is the right fit for the AVP line, performance aside, plus the half dozen or so IOL they drafted the past couple seasons. But Strange could miss training camp. It's complicated. But paying Onwenu $20M seems like a lot for what he offers.
On Duggar - the Pats have another big in-the-box safety in Peppers, plus the hybrid who didn't really play last year in Mapu. Mapu may be better at roving LB, but he was drafted at 216 pounds, where Duggars was drafted at 217. They really need a center fielder like McCourty. Getting Duggar back LT would be great.
It would be really nice to hear of an extension for Barmore and re-signing Henry.