He was never going in the 2nd round. Just because fans come late to the party doesn't mean NFL scouts do. One game will never define any player in terms of draft stock.
Walterfootball has him going #4 to the Jaguars in their latest mock. But they forgot that they had him and still have him as the #8 defensive end in the draft (does not include defensive tackles which are a separate list).
"Thomas has good speed off the edge with strength and physicality. Off the field, he is getting high marks for character and work ethic. Thomas would probably fit best in a 3-4 defense as an outside linebacker. Sources say they are grading Thomas out a second-round pick for the 2017 NFL Draft."
He wasn't on most first round mocks prior to meeting UNC. Of the ones he was on, Profootball focus had him going #27, Draftwire had him going #32. Washington Post had him outside the top 30 under "other players under top 30 consideration".
Nov 28. Solomon Thomas Jr. DT - Arguably the best defensive lineman in the Pac-12 this year, Thomas is athletic and versatile with the ability to play a number of positions at the next level. Prediction: Since Thomas is actually a redshirt sophomore, I think he comes back for his third year of on-field action. Range: Early-to-mid-3rd round.
I just hope we're not the ones overreaching for him based on 1 game.