Despite the obsessions, he had a point here.
Losses are big part of a learning process. That's why coaches of young rebuilding teams call a timeout to run a last game play losing by 2 or for 20. If a coach wants to develop players, he'll try to translate what the team worked on in practice into real games, even if they're gonna lose those games.
Like you said the game was lost very long before and it could have been a good time to try something different than usual, why not allow young players to gain valuable compe ive experience in a lead role?
Messina trusts in Manu and Beli, he knows them, but that was a bad decision. Manu wasn't playing great, the best two point guards of the team were injuried, why not play the young guys?
Even Pop did it against the Pels and Leonard, Joseph, Green, got us back in the game.
The Spurs'll try to build around some FA bigman star, Tony and Kawhi...they won't sign the other guy until the summer, Tony didn't play...it made no sense to bench Leonard.
Manu is still great but 37 years old, he can't win every battle for us. And the Spurs can't afford to let him to run the offense in the clutch time all games.
It could be a good learning experience to let Kawhi and the other guys do things that they otherwise couldn't do in more crucial games.