Old man game doesn't work at the 2 or the 3 because there is no way to hide on defense. Every team has an athletic 2 and 3 that can bust geezers off the dribble. The NBA players that are effective late into their career, like Ray Allen and Paul Pierce, still hit a wall in their early 30's, and became secondary players after that. Pierce's last season above 15 ppg was when he was 35. Ray scored 18 ppg at 33, then had two seasons of 16 ppg, then dropped to 13. Michael Jordan averaged in the 20's at 38 and 39, but A) He was Michael Jordan, and B) that was after 3 years of resting his body. Kobe averaged 27 ppg at 34, but then played 6 and 35 games the next two years, and the Lakers were abysmal in his final year when he averaged 17 ppg.
Drexler averaged 18 ppg at 35, and then he hung it up. The last time Vince Carter scored over 15 ppg in a season was when he was 31. The next tier of players like Rip Hamilton or Tracy McGrady hit the wall around 30.
Those guys abive are first ballot HoFers, and they mostly hit the wall around 33 to 35. None of them carried a team deep into the playoffs in their mid-30's. Lebron is turning 35 this December. He is a freak, and can probably be the #2 to someone like AD, but if the Lakers end up with Cousins or DRose out of free agency, they aren't going to be much better next year than they are this year.