I've been thinking about this as a Vigil owner in dynasty. It's tough to know - I don't put any stock in PFF grades, and all the Bengals LBs seem to grade poorly outside of Burfict, so I don't know if that means they're all terrible or the scheme makes them look bad for whatever PFF are doing. In any case, I have liked Vigil a lot and viewed him as a key dynasty piece, but reading through some Bengals fan boards, most fans think he's pretty bad and want him replaced (or moved to the weak side, where he performed better). He's seen as a liability.
I haven't watched many Bengals games so I don't know if that's true but you kind of don't think about it as long as a guy is racking up tackles. I don't know what the Bengals think of Vigil, but from what I've been reading the last couple of weeks, they do seem pretty high on Evans and plenty of people liked him pre-draft and saw him as a value pick, so I'm trying to find a way to keep him on my roster in the off-season, even though I own Vigil as well and there are other LBs I'd also like to stash. I do like it when guys get a brief opportunity and they put up IDP stats though - not everyone does that and Evans has. Whether he's actually played well doing that from an NFL perspective, I don't know.
Having said that, It's hard to see a path to consistent IDP value for him, at least next year. I expect Minter and Rey won't be kept, but Vigil and Burfict you'd think will be there and that's plenty of competition for tackles. So it depends on where he plays I guess. He at least would have good injury value if one of those two missed time - but as always, depends on the depth of your league.