Sherman isn't a safety scheme fit. For Quinn's scheme, what we really need is a safety whose more adept at playing the single-high look. Quinn has played a lot of cover 1/cover 3 historically, and you need that deep middle drop ballhawk type safety. Now, obviously, most if not all teams could use a player with that skill set, but it's particularly important in Quinn's scheme. I don't think we have that player on the roster right now. Wilson I think will fit in great in Quinn's scheme, but not as the deep middle guy.
The nice thing is that there are a LOT of good safeties set to be free agents. Not all of them will make it to free agency, but some of them might.
Justin Simmons - the premier safety that could be available, although he likely re-signs in Denver. Is more of an all-around type player, but could certainly fill this need as he does almost everything at an elite level. Huge contract required.
Anthony Harris - great player, but not a fit for this scheme in my opinion. Better in split safety looks.
Marcus Williams - could definitely be a fit.
Marcus Maye - probably my favorite option.
John Johnson III - probably my second favorite option.
Malik Hooker - if we don't want to spend big money here, Hooker actually is perfect for this scheme. He played a little out of position in Indy in my opinion, and also has injury concerns, but could be a cheaper depth signing that fits the scheme.
Keanu Neal - not a fit for the deep middle role, but obviously has a history with Quinn and could fit into the D similar to how Donovan Wilson does.
So, Sherman may fit here as a corner, but not as a safety. We also have the possibility of bringing back Xavier Woods, and while there's 2 to 3 guys on my list above I think would be better fits, the price might be right with Woods. I think he can do a serviceable job in Quinn's scheme.