"where is the toughness going to come from"
Spurs aren't tough. Tonight was a great test, to hold off DAL late charge, and do it with FTs in crunch time, and Tony hitting a big one. But the Spurs are not a tough team, able to get it done in the face of tough compe ion or when they aren't playing well, being their own worst enemy, but find a way to win anyway.
But Tony M plays so little, does so little, that last game we were over the moon he did anything at all and did it at just the right time.
"toughness" means to me if the big tough-guy doesn't get RBs, block shots, and not miss his defensive assigments. I just don't think TMass can, in the tiny minutes he gets, have an impact one way or the other, and his negatives offset his positives, in nearly all his minutes.