Sharpton has filled in for DeMeco at MLB a couple of seasons ago and was better than early-post-pregnancy Cushing at the position, so I struggle to see where the short memory comes from. I'm willing to bet that part of the reason they felt comfortable cutting Ryans was that they were expecting Sharpton to be healthy for pre-season.
The dude is injury prone, but at the same time we have Dobbins and Ruud in the mix there, Dobbins knows the system and is a nice fit to it, plays pretty well every time he gets snaps, and we all know that Ruud is a low risk pickup who will be very solid if he can recapture his form from a few years back.
Sharpton will take a little while to get up to speed I expect, but in a month or so I wouldn't be surprised if he's the starter.
Bradie James is obviously the #1 but I get the impression he has glaring weaknesses which we have to gameplan around, getting stronger around him will help us out there, and Sharpton has run the D in his time too so may just bump him down a spot.
Nolan was the backup that everybody loved when his play was limited, and has a big play in him, but his coverage skills maxed out at below-par, and the more snaps he got the worse he looked. Demps offers us more in what is a high snap count role at #3 S in this D and the coaches and players obviously don't see Keo as the problem on STs, and I believe still see him as a project at S too, of course one of Brandon Harris and Roc Carmichael aren't going to make the grade at CB given that we are fairly young, strong and tied up in contracts at the 2 starting positions and fairly strong at slot too, although McCain is hitting FA, so maybe one of them gets moved to S in the offseason?
I think there is the old short or selected memory happening to an extent, Nolan was not an option at S, while Sharpton is potentially an option at LB, I don't think we lose anything, but we chance our arm at gaining a lot.