They have a dilemma in that it’s something they need to sell to the players. The simplest solution seems to be keeping both as inevitably, Darnold probably gets hurt at some point next year, but the injury hasn’t given them a chance to prove that they were right.
Darnold at 27 though, there’s still a reasonable chance that he can still be the guy. I would keep both and see who emerges.
It's not hard to sell the players, you could have said the same thing about letting Cousins walk. (I remember 'Jefferson will ask for a trade if Cousins leaves' discourse)
You don't give him big money or long term, because
A.) This might just be Case Keenum 2.0 and
B.) you have the 10th overall pick waiting in the wings.
It's even different than the Keenum situation too since they had no QBs under contract going into that offseason. Now you have a 10th overall pick. You can even keep Jones around if you want and say that's this years Darnold.
I don't give him big money or long term. A year on the franchise tag or a 1 year deal worth 20/30 million (I'm not sure he takes the latter) fine, but I'd rather take my chances with McCarthy and use that money on defense* and interior OL.
If Darnold goes somewhere else and continues this play and JJM is a bust, then you eat your crow, but it's the right move, IMO.
*Top 3 CBs and Cam Bynum are all UFAs, Smith is old and might retire, and the DL consists of Harrison Phillips and journeyman.