That looks great on paper, but I don't think that first group would spread teams out like we'd want to. Mack and Burke need to (I think they will) improve their perimeter shooting. Roby has been inconsistent beyond the arc, although his mechanics are there. Just needs confidence. Johnson's defender would be waiting in the paint to protect the rim at all times.
A lineup of Mack, Jervay, Cheatham, Kavas and Roby would be a nightmare to defend. Would have great space and room to attack off the dribble. I know the narrative is that Roby needs to play his natural position to better utilize his talents, but I disagree. I felt Roby was at his best this year when Tanner was on the bench and the other team's big was forced to guard him. The big has to come out of the lane and defend on the perimeter, and Roby has the ability to blow by him off the dribble. He also used his quickness and ability to finish with either hand to score on guys like Happ, Teske and Fernando down low. On the other hand, when the opponents "4" defends Roby (players with the archetype of Miles Bridges, Juwan Morgan, Nigel Hayes, Bradzeikis) they are able to stay in front of him and often times force a turnover on the perimeter. And with a lower center of gravity, they push him off his spot in the post. At the college level, the way the game is played today, I believe Roby is most effective at the 5. It led to foul trouble this year, but Doc's pretty good at teaching great team defense with undersized posts.