I don't see the numbers you're coming up with unless you're counting guys that seem like a stretch to me. Also, think of the distribution by class. We have a group of upperclassmen that could be very good in 2017 if everything pans out, but the cupboard is bare behind them.
Upperclassmen
Senior - Vickers
RS juniors - Johnson and Kongbo (that's assuming that Johnson get the RS, Kongbo moves to DT and that both of these guys stick around...some of these are big "ifs" IMO)
Juniors - Tuttle, McKenzie, and Picou
Underclassmen
Whoever we sign this year and Andrew Butcher.
That's 6 upperclassmen, and several of them have question marks around them. I wouldn't be at all surprised to see Johnson and Kongbo move on for whatever reason. Tuttle can't catch a break (no pun intended) with his health, and him and McKenzie could both go pro early with a breakout year in 2017. I seriously doubt Picou is ever going to be a quality DT at the SEC level.
What else do we have? Maybe Phillips moves to DT? That would probably be a project. The VN legend Paul Bain? I'm highly skeptical. Does Mosely move over full-time from the OL? He already flamed out at DT once. Butcher? He hasn't been able to stay healthy or crack the depth chart in the 2 years he's been here.
When I look at that list I see a lot more questions than answers. Not taking a a single HS DT last year was a really bad move IMO. If we don't make up for it with numbers and quality this year we'll probably pay a heavy price for it in 2018 and/or 2019 and beyond.