as longtime Spurs fans, y'all should know Pop's way of thinking by now. He coaches like this is the military. Mills has been here for 10 years, he's a military veteran, so he will always be out there instead of Walker who's only been here for 3 years. Skillset does not go into the evaluation. Even on defensive posessions at the end of games Mills will be out there, which is absolutely idiotic.
Aside from that Pop drawing up a play has become a joke. When was the last time he drew up a successful play? Was it that Belinelli 3 against the Kings last season? He let DeRozan go 1-on-1 against the Rockets best defender, PJ Tucker. All he had to do is call for one screen to get Tucker off DeRozan and that shot would've been a lot easier.
Additional to that, Pop has been had the team come out flat for years now. I don't think a lot of players take his motivational speeches serious anymore. And if we had a lead at halftime, we come out flat in the 2nd. Back then when it happened he had Manu and all he had to do was sub in him and he'll give the team the neccessary energy, that is gone now.
Pop is also not as experienced as a coach as people think. He coached Aldridge like he was Duncan, he coaches DJ like he's Parker, he coaches White like he's Manu and he's using DeRozan like he used to use Nephew when he became the #1 option. He's had Duncan/Ginobili/Parker for most of his coaching career and clearly doesn't understand how to change his approach without them.