I actually don't think Joe Johnson is doing bad at all. His decrease in shooting efficiency come from going from being the 3rd option on a team to becoming the 1st option on a team. Now he get's the opposing teams best defender, teams focus on him etc, he's still averaging like 19-4-6 and pretty good percentages.
Quentin Richardson is also a bad example. His percentages on the Suns didn't really go up in comparison to when he was playing on the Clippers. His PPG went down in Phoenix because of less shots, and even as the 4-5th option on the court he was still shooting under 40% from the field and under 36% from outside. His numbers in NYK are bad because he's playing 24.5 MPG, he's not a main guy offensively, so less shots again, and their offense is ugly in terms of ball movement.
With a guy like Diaw, it's about the system and the confidence. His improvement isn't related to him getting to score more. If you look at his first season, he averaged
4.5 rebounds in 25.3 MPG, that would equate to
5.9 RPG in 33 MPG.
In his second season, he averaged
2.3 APG in 18.2 MPG, which would be
4.1 APG in 33 MPG. This year he's averaging 6.4 RPG and 5.9 APG on a faster paced team. In comparison to other years he's playing SF/PF/C as opposed to PG/SG/SF, so obviously being close to the basket with more rebound oppurtunities, you'd expect his rebounds to go up. Also in comparison to other years, his teammates are a lot better in terms of making shots and finishing, and this system emphasizes ball movement, so you can see where the assists increase comes from. The biggest one I see though is D'Antoni's confidence in him. Mike played in Europe before, and when Boris does something like get a travel with the Euro step, Mike encourages him and tells him it's okay because he knows that's not a travel in Europe.
In Phoenix the "improvement" of players isn't really them getting better. The improvement is based on them playing as a cohesive unit. Mike D'Antoni is the president of this, because no other coach really does this. Nash is the vice president in that because he's willing to follow what the coach says, which he should be happy to because it gives him a lot of freedom that many strict coaches don't give to their PG's. He (Nash) didn't play like that in Dallas because the coach wasn't interested playing like that. A guy like Raja Bell, James Jones, Eddie House etc have not become better, but they're getting to shoot a lot more, and this makes them excited to play on both ends. The inclusion in the offense makes guys want to play better on the defensive end. No one feels left out in the team, so you don't get the normal sulking of role players that you would.
Making teammates better is interesting. In general, PG's should make teammates better, and most good PG's do make them better. Big time scores are also able to make teammates better if they're willing to because of the attention they draw. A good big man can make teammates better because they suck the defense in. A good big man who's a post up option, can make a scorer better because he has to force less shots, and when he gets stuck those 2-3 times a game, he can pound it inside. Those 2-3 less bad shots can change your FG% drastically. It can change you from a 41% FG shooter, to a 45% FG shooter.
Sometimes people mistake a player decreasing in rank offensively as him being made better. In general, going from a first option to a second option means someone else is a better scorer, and the opposing team will not focus on you, so your scoring percentages should go up.
Things that can help make teammates better are leadership, work ethic, trust in teammates as a star, and teamwork. Some stars with good work ethic have that rub off on teammates, trusting in teamates offensively makes them want to work for you defensively. Some people want to say well these guys are big men, they shouldn't care, but that's how we are. Teamwork builds chemistry, and when a team develops great chemistry, they're a better team. So being a player that emphasizes teamwork, though also knowing when it's your time is important.
Now we know Kidd didn't do some surgery to fix Vince's knees or anything like that, he didn't make Vince permanently more durable. But he's influenced Vince in a lot of ways, and he's done that to a lot of players. K-Mart isn't nearly as impressive without Kidd, and he's no excuses, he has a great coach, great passing PG, and Camby guarding his back...he should be playing his best ball ever...but it's not the case.
Carter wasn't injury prone the year before though, the problem then was when he fell on Bowen's foot and rolled is ankle. He played 73 of 82 games. In New Jersey he's actually missed more than 1, after he got there he was out for 2-3 games because he still had a hamstring injury. He also missed one yesterday due to something in his back, but I think that was needed since he was clearly playing horrible the 2 games before that. I think people overexaggerated the extent of him missing games due to tick tack injuries. Kidd has affected his aggressiveness on the court though, but like in the beginning of the season he was not that he wasn't being aggressive, he was just trying to play too much of a team game, and they [Kidd, Frank, RJ] had to keep him in check