Read again - that lineup was still scoring with the best of them over that big a number of possessions. Kings 3 leading scorers average above 60 ppg on the season. Obviously it is somewhat inflated by injuries and need to take a bigger role, when one of the 3 is missing, but you can reasonably expect them to average above 55 points, when they play together. So what would you like him to do on top of defense and rebounding? Score more? Kings don't need him. Create for others? He doesn't control the ball nearly enough. Plus he keeps TOs low. He doesn't shoot, right? Ok, legitimate argument. Ilyasova and Millsap are better shooters by a big margin, Green is a better shooter by a margin, Nene and Zach are similar and Splitter has no range at all, so even though he provides marginal spacing, it's still there. Finally, maybe, you want him to chase more steals and blocks, when he was already a part of elite defensive unit?
Kings need another solid big. Given that JT works well with DMC and is ok as a backup C, preferably Kings should get a low usage defensive-minded starter like Taj Gibson (a lot of value can be covered by removing protection from already owed pick, that Kings are likely to lose next year anyway) or Amir Johnson (is a reasonable target as an FA, if you start recruiting him on July, 1st) to start alongside Boogie.
Not sure, if anyone is following Hornets, but Noah Vonleh got some minutes late in the season. He looked ok inside and pretty good defending perimeter, but also being overaggressive and reacting slow from time to time; offense was even more of a mixed bag. That's how rookie bigmen look in the NBA after just 1 year in college. That's why only WCS has any chance to produce right from the start, and even with him expecting more than a 20 mpg rotation player is pushing it for PO contender.
As for Celtics Kelly Olynyk is actually their best big defensively and offensively, and it's not really close!
Going through Nets roster Teletovic would be an excellent fit, Plumlee is measuring towards the bottom on D - either Worlds or getting starting spot got to him.
What I want JT to do?
Rebound without fouling by not establishing position early and pushing guys in the back. Defend the pick&roll by rotating properly and cut off penetration by going straight up.
Being able to catch passes in the paint and finish through contact. Being able to set good screens and either pop out for a jumper or roll to the rim hard and being aggressive. Use his great physical tools for running the floor hard.
Thats basic big man stuff and JT is simply not good at it. I couldn't care less, if he blocks shots or gets steals, when he would be able to do those things. And to be honest making those plays has a lot to do with effort, reading the game and paying attention - this is something a veteran must be able to do.
Yes JT was part of the lineup you mention, but as sweet as the stats look, it's very easy to tell that JT is not even a mediocre PF just by watching the game. Stats don't tell the whole story and outside of man defense JT's impact on the game is just too small.
Zach is not even on the same planet like JT, when it comes to all those little, valuable plays. Green is a top candidate for DPOY and rightfully so and is a better rebounder, a fierce competitor and a floorspacer. Nene, when healthy, is a force on offense and has so many moves in his arsenal, that comparing him to JT, who has a jumper and a halfhook, is insane. Splitter has great value as a passer and uses his length pretty well. Millsap is a better defender and a floor spacer.
Come on now - I understand, that JT is well liked here, but he is so far off those guys you mention....
Kings need a PF, who can make plays on defense and offense. Part of our struggles is, that we rely too heavily on DMC on offense and defense. We are lucky, that we have a player, that's able to carry teammates like JT. But this doesn't mean, we shouldn't try to improve our biggest position of need - and thats the starting PF.
JT is a serviceable third big for the remainder of his contract, but to be honest: when you take a close look at guys like Seraphin, Speights or Koufos he is not even a very strong third big.