I wanted to follow up on Nate's article from yesterday by looking at some on/off ("with or without you") stats for Jarrett Jack. The idea is to see what are the "effects" (if you'll allow me the statistical laziness of using that expression in the context of the non-randomized experimental setup that is the NBA) of having Jack in or out of the lineup on his teammates. There's an awesome site called nbawowy.com that let's you pull these kind of data. (You may have heard of it.)

First, let's look at some basic shooting stats with JJ ON or OFF the court (as denoted in the first column below):

You can see that differences that are blue are positive, meaning that the player actually put up better numbers with JJ off the court. So, for example, Stephen Curry is better across the board, in terms of shooting stats, when JJ is on the bench. Klay Thompson and Harrison Barnes don't really get much better or worse in any category. The players that seem to be the most affected one way or another are the bigs: Ezeli, Lee, Landry (especially), Bogut, and even Draymond Green. This is interesting and perhaps suggests that one of Jack's strengths is getting bigs involved in the offense. Except for Ezeli, who apparently shoots better with Jack off the court. For some reason that I can't explain.

All in all, it looks like --- again, aside from Ezeli who is a small part of the offense --- Curry is the only featured player who shoots somewhat better when Jack is off the court, while the other wings don't see significant movement one way or another, and the bigs seem to decline quite a bit.

The other area where I think it's important to take a look is ball handling. Specifically, what is the effect of having Jack on or off the court on turnovers and assists? Let's see.

Not surprisingly, the turnover rates and %'s (TOR = TOV per 100 team possessions; TOV% = TOV per 100 individual plays) go up for the guards and wings who have to handle the ball more without Jack. David Lee's turnovers also go up, but he handles the ball quite a lot. It is perhaps surprising that the turnovers for Landry and Bogut decrease considerably when Jack is off the floor. My only thought is that maybe Jack gets them the ball in more difficult situations than when Curry is the lead guard. It should be noted that overall the team turnover rate (TOV/100 poss) goes up from 13.8 to 14.5 when Jack is not on the court. That's a fairly significant increase, but it's not devastating by any means. It's actually less than I would have thought given that Jack's main role is supposedly to sop up ball pressure from his teammates.

As far as the assists go, these stats are also not surprising. When Jack is off the court, his teammates, especially Curry, tend to amass more of them. Once again, though, at the team level, things don't change so much. When Jack is on the court, 58.7% of field goals are assisted vs. a slightly lower 58.2% when he is off the court. To put this in perspective, the AST% drops from 59% to around 55% when Curry comes off the court.

Looking at the stats I presented here, the case for Jarrett Jack is not obvious. And I say this as someone who has been of the mindset that we really need to re-sign him (note how that is spelled young folks!). I think the main question is who replaces him. In the playoffs, we were obviously very successful with the 3 guard lineup. How do we replicate that success without brining back Jack? I'm Kent Bazemore's #1 fan, but I don't see him stepping up into that role. (O.k. now I have to admit that opinion probably disqualifies me from #1 fan status.) Also, given our cap issues, I think it's easier to re-sign Jack (perhaps, at a premium, but it's not my money), than it is to pick up a player his equivalent for under the MLE. Bringing back Brandon Rush (assuming he's healthy) will definitely help, though, and I expect Rush (again, if healthy) would pick up fairly heavy minutes left behind by Jack. Furthermore, we can expect some improvement in terms of ball handling from Klay and Barnes. My hope would be that if we lose Jack, all these things add up to something capable of replacing him.

But right now, if you put a gun to my head, I would still lean towards re-signing Jack and just not messing around with a good thing.