Good to hear about Thompson, but he's a FS, and I'd rather have Heath backing up FS over Thompson. He's also on a one year deal til free agency. He's not a player to invest development time on. No reason not to upgrade from him.
We don't have a single good in the box SS. That's what I would be addressing first with a new signing. Getting an overall SS is better. That frees Heath up for special packages and backing up both starters.
Maybe Wilson will be an ok SS, but I'd rather get a vet who is better.
Wilson back, bye Frazier.
Sign/trade for veteran SS, bye Thompson.
Thompson did start 16 games at FS in 2017 for another team.
I'm not sure how you compare Thompson vs Heath at FS.
Both are free agents after the season. Thompson won't cost much to re-sign unless he becomes a starter this season.
Frazier is good in the box against the run but Kris Richard does not appear to trust him in pass defense; although he did start games 1 and 2 of 2018.
Wilson is the upside player. He played primarily at FS in the preseason but his tackling was good and he is a sturdy player.
I don't see them getting a vet that is an upgrade this season. That would require a trade.
Hopefully Wilson is the real deal at SS but if not they do need to consider drafting a Strong Safety next year.
There were a lot a decent Safeties in the draft but most of them were Free Safety types.