I suspect Jenkins is gone just because of a money/numbers situation.
1) We have 3 guys, Pickett, Raji, and Neal making some big money on the d-line. Giving Jenkins the contract he deserves breaks the "too much money at one position" guideline.
2) We have a pretty deep D-line currently. Right now, we have Pickett, Raji, Neal, and Green as the linemen on the roster, under contract for next year, and good enough to start. Thats 4. Jolly would make 5. Wilson and Wynn make 7. Jenkins would be number 8. 3-4 teams (typically) only carry 6--SIX--on the normal 53. Assuming Wynn and or Wilson improve, we already have some difficult decisions to make at the d-line and we haven't even. . .
3) ...Drafted anyone yet. We'll likely pickup at least one d-lineman in the draft. Gotta keep replenishing the stock!
4) I'd say there's an incredibly small chance that Harrel is back next year, at least as a camp body. I'd put the odds at him making the roster at something like 1 in 1,000,000, but! He's rested, likely won't get signed anywhere else, and we could get him for the veteran minimum for 2 years. No signing bonus, etc etc. If he's still no good, we get rid of him at cutdown and spend $0 more on him.