Some things that a human coach might consider doing in game 3:
1. Actually have defensive rotations off the ball outside of Gobert. The Mavs don't have a lot of great shooters. Quin's approach has been to allow the "worst" shooter to have a wide open 3 with no resistance. If Maxi Kleber is 7-9 from 3 and is wide open in the corner, try defending it. This should be really easy to implement. When Gobert helps, someone else covers rotates to cover the guy Gobert was guarding. Make them complete at least one more pass, or a more difficult pass to the wing, instead of allowing a wide open uncontested 3. I think pro players should be able to handle this simple concept, but who knows at this point.
2. Acknowledge that Mitchell and Conley can't defend, so trap every time they try to get the switch. This is what the Mavericks do with Bertans, and although it opens up some gaps, it's better than having Bertans on an island guarding 1v1. Give up on the idea that Conley and Mitchell can stay in front. Trap and get the ball out of Brunson's hands.
3. Go full Harden mode and allow the drive. Accept the reality that we cannot defend, so instead of trying to stay in front just give up and try to rotate out to a shooter. Gobert is going to have to rotate anyways, so you might as well try to be useful. This works great in tandem with the first point. This may sound crazy, but Luka coming back might actually help us in this regard. Brunson may play like Luka Doncic against us, but he's Jalen Brunson and we haven't accepted reality that he will dominate our perimeter defense. With Luka, Quin might treat him like Harden and deploy the same type of doggy style defense. Some combination of treating Luka like Harden and Luka not being 100% might work.
In any case, I think we need to give up on the idea of staying in front of the ball handler. We don't have the defensive talent to stay in front of Brunson and Dinwiddie. Conley and Mitchell are two big of liabilities and everyone else is having a hard enough time anyways. We know they're going to get burnt and the solution has to be better than leaving Kleber wide open from 3 or giving up the free layup. The Mavericks still chop us up if they're forced into their own version of the blender, but I prefer the 3v4 defensive situation more than the 1v0 situation where it's Maxi Kleber vs air at the 3 point line. If we wanted to rely on proving some kind of resistance at the point of attack we needed to make trades. Can't do that now. Understand that we cannot defend on the perimeter and Gobert will have to help. It's a losing position but we have to live with it. We can't live in fantasyland where Conley and Mitchell can defend Brunson or giving up uncontested corner 3's is a better outcome.