Rudy Gobert at the 5 is better defensively than Rudy Gay at the 5--even against a small-ball lineup. Gobert has no problem guarding guys like Batum on the perimeter. He did great with it in the regular season, in Game 1 and in Games 2-5. He was injured in Game 6 and Quin concocted a circus defense designed to cover everyone else's weaknesses with Gobert guarding Mann. That clearly didn't work!
But Gobert on Batum, Gay on Kawhi, Royce on PG, Conley on Reggie and Spidey on whomever the Clippers play at 2 will work just fine defensively in crunch time. I absolutely agree that it would be nice to have a Thybulle or a Beverley to bring in as a defensive specialist at the guard position. However, even if they had such a guy, I question whether QS would really sub out Donovan and/or Conley--even on a defensive set inside 2M.
If Royce's job can go back to being the defensive specialist guarding the opponent's best wing (or point forward), then he will go back to being the best in the league at that. He's got the perfect combo of quick, strong, long, smart and nasty. The option of using Gay at the 4 allows Royce to be that premier wing defender. Playing him at the 4 didn't work.