Pop likes that veteran leadership that those two bring. For Pau it's that "elder statesman" and championship experience that they lost when Duncan retired. For Patty it's the "Spurs way" corporate knowledge guy that the Spurs had in Green, Manu, and Parker last year. Just a guess but those guys maybe most effective to the team outside of the games, giving the coaching staff a stability cushion to the team during practice, on the bench, outside the gym, during losing streaks etc.. Tony and Manu were not going to be around forever, Kawhi didn't seem to have that locker room leadership, and LA just started to get things together last year after wanting a trade. Tim and Manu will show up to practice from time to time but it's not the same as being on the floor with a bunch of new players night in and night out.