You can still get enough pops from age 23-24-25 if you train properly. Question is if that's worth it for this player.
In any case, even the best shooters can have off days where they can't find the basket. The advise to get more IS is good because great players will try to get to the rim if their jumpshot doesn't fall, but your guy can't. Also, good passing is also important so he can pass the ball if he doesn't have a good shot (now instead he'll just shoot himself).