I disagree, Kristaps is shooting the ball awfully, but the main difference I see is that he's passing up shots that earlier in the season he was taking to then go and try to create a better shot (which doesn't turn out to be). At season's start, everytime a point guard ran a screen and roll or screen and pop play, KP took the shot as soon as he got the ball. He wasn't trying to drive as much. Now it seems he feels his jumpshot is off, so he's trying to create more off the dribble and the results are sometimes ugly.
Overall though you look at his impact on the game, and I'm not going to make this into a silly Melo vs KP debate, but the beauty of KP as a player is that he can have an off night on offense and still shine. 10 boards. Many good defensive anchoring plays. That's his value. He has a very good +/- impact on the team for a reason. Even if he's missing shots, if you look at how teams defend us this year vs last year (or early in the season) they are no longer letting their bigs leave KP alone. This allows our guards to drive into the paint and get good, better looks at the basket.
KP needs to look at tape and see how he's hesitating a little and forcing himself into bad spots. He needs to take the open shot. He isn't a role player who can be on or off. He's a great shooter. When he has an open look just catch and shoot it.