I agree he's done well the last two drafts. I also agree he's had some drafts that were shaky at best.
If there's 1-2 players left from 2016 (for example), that's not a great draft but not terrible either, depending on those 1-2 players and what you got from the others. 7 years is a lifetime in the NFL. Agree if you get nobody long term from a draft (i.e., 7+ seasons) then you probably had a bad draft.
It might be helpful to look at a draft from whether the player made it to the end of their contract, and if they were signed to a 2nd contract.

Picking on 2016 randomly (a TT year, inind you), GB still has Kenny Clark. They got meaningful snaps from Kyler Fackrell and Blake Martinez, and they gave a 2nd contract to Dean Lowry (who was wisely allowed to sign a 3rd contract with MIN and is on IR). That's not a franchise-foundational draft, but it's not horrible either. Sure, you'd like to have picked Tyreek Hill over Trevor Davis in R6, and maybe not give up so much for Jason Spriggs, but if you go back and look at that draft and how some other teams did, it wasn't bad.

Someone in GB's pro personnel scouting is pretty good at finding guys who were basically on the scrapheap - Campbell, Douglas, Ballentine, Rudy Ford. Even getting Jared Veldheer off the couch.
Gute's done pretty good in FA too, and we saw with Smiths/Turner/Amos.

I'd give Gute a B grade. He's not GM of the year, but he's not horrible either. I think having a lot of picks helps -- it's like swings at the plate in baseball. At some point -- possibly this upcoming draft -- he's going to have more picks than roster spots, and that will be interesting. I'd expect him to trade for future picks or trade up in that case. (Personally, I'd prefer trading for future picks. It's less satisfying, but I'd happily part with a R3 pick to some team for their R2 in the next year. Don't think teams do that much anymore though.)