I would play Paschall instead. Rudy Gay is a better rebounder, but I think that this advantage is overstated by the raw rebounding numbers. The majority of rebounds are not highly contested, and box outs don't get counted. What really matters is how the team rebounds with each player, and not necessarily the individual rebound totals themselves. Rudy Gay has gotten a lot of rebounds himself over the past few years, but his teams haven't necessarily rebounded better with him on the court. This year when either Gobert or Whiteside on the court, the Jazz rebound more effectively with Paschall at the 4 versus Gay at the 4. Like I said, still advantage for Gay...but probably overstated by the raw numbers.
Paschall is so much more lively on offense. If he's guarded by a smaller player or see's a crease in the defense, it's an easy bucket because he's so explosive and strong inside. We're getting almost zero value from Gay as a shot creator, who is at this point more or less a shaky spot up shooter. It's not exactly fair to exclude Gay's hot start, but he's shot 28% from 3 since his first 6 games. Shooting wise, I think I would still give a slight edge to Gay, but Paschall's improvement and Gay's regression makes that a toss up IMO. Given Paschall's huge advantage as a scorer inside the paint, I think he's pretty clearly a better offensive option.
Defensively it's more of a situational thing. I think Gay is pretty decent at guarding actual bigs man to man. You can't post him up easily, but he gets cooked in any kind of action. Paschall doesn't handle true bigs well inside, but he has the ability to switch and can be your primary defender on big wings. I do think his man to man defense is a little overrated, however. I think Gay is pretty much a defensive 5 at this point, and that can have value. Paschall is just a different type of defender.
Overall, I feel confident that Paschall should play instead of Gay....or we should at least keep trying it. There's no question he's been a better player so far. Gay could still factor into the rotation as an alternative to Whiteside if he's struggling against a certain playoff matchup.