Greetings residents of Stiffnation, I come in peace and basketball nerdom. You may wonder why I'm here or why in the world I care about TPM. I came across Mr. Rasmussen's nifty stat while hanging around NetsDaily.com after your game against them (gotta check on my boy D'Lo ya feel?) and noticed a most interesting comment concerning a fan made stat that aimed to improve upon the much maligned +/-. Always curious, I made a point to follow the link provided and learn about the stat called True Plus-Minus.

I was immediately intrigued. I think TPM is an awesome idea and even has some advantages over RPM, the supposedly best stat to gauge player effectiveness now a days. First off, it's a descriptive stat and not a predictive one, which is already a step in the right direction in my opinion useful for evaluating players and seeing how they actually have contributed instead of how they could contribute. I like how TPM isolates the play and only includes the participants directly involved instead of accounting for everyone on the court. I also like how it's looking at aspects of a play that aren't recorded on a stat sheet. It definitely isn't a perfect stat, especially since it's recorded by hand and involves a certain amount of human judgement, but the fact that it is basically a contextual plus-minus, which is the big weakness of PM, is awesome.

Anyways, after educating myself I decided I would take on the duty of trying to track this stat for the Lakers. After having watched and recorded TPM for every game the Lakers have played to this point, I have several questions regarding exactly what qualified as a "credit" or a "debt" in certain game situations. I was going to wait until Mr. TPM himself made his standard post in the Nuggets-Lakers post game thread on Sunday to ask these questions, but after glancing at his most recent TPM update I have a feeling that my numbers might be a bit off and want to clarify my confusion as soon as possible. Any change in the formula on my end means combing back through every single Laker game again, something I've already had to do once on my TPM journey.

Questions

With all that long windedness out of the way, here are my equally long winded questions concerning TPM. While kind of directed at one Mr. Patrick Rasmussen, I'm open to anyone answering these:

• In the situation where player A is in an assist situation and player B, the shooter, is fouled, but doesn't make the shot, does player A get credit for the points made from the free throws? I realized today that I was giving credit for free throws after a made basket, but not after a missed basket since the assist is technically nullified. I figure that credit should probably be given after re-reading the OP today, but I wasn't sure and have not been awarding credit for this.

• You mention offensive rebounds in the credit section as well as steals and blocks, but never do you mention defensive rebounds. While I wouldn't give credit for an uncontested rebound, what about a contested defensive rebound? You already have stipulated that a player is debited when they fail to successfully contest for a rebound. Should they get the same in terms of credit if they grab a contested defensive rebound that leads to points on the other end?

• While it is easy to assign credit to someone who gets a steal, how do you determine who is credited if there is a non-steal turnover by the opposing team such as traveling, errant passing, or 24 second violation? Does it go to the person guarding whoever made the turnover? Is no credit given since no one was technically involved in creating the turnover?

• In the case where an opposing player blows by player A and attempts a layup which is missed but is then contested by both teams and tipped back in by a teammate of the opposing team, does player A still debited for the play? On offense, I consider an offensive rebound to reset the assist credit even if it is just a tip in. Does it work the same way on defense or is player A still responsible since he was still blown by, creating the chance? Or am I scoring the credit wrong and an assist should still count even if the shot is missed and then tipped in by another teammate?

• How is debiting assigned for screened defenders? You specified the details for how to score the big man on defense in the case of a PnR, but didn't mention the screened player. Is it assumed that since he is screened then he doesn't get debited if points are scored? I will sometimes debit the defender if I determine that he could have successfully gone under or over the screen to stay on his man,but this has been a very grey area for me. If he partially gets around the screen and is tailing his man when he scores, is he debited then? I have usually been debiting in this case.

I know these are pretty technical questions, so tell me if I'm overthinking things.

A New Idea

While I was recording TPM, I also noticed something that could potentially be an add-on to TPM that could help give even more context to how a player is involved in the game. This add-on is what I am tentatively calling Involved Possessions (IP).* It's a stat that shows for how many possessions a player was directly involved in an outcome (aka received a TPM score). Basically, as I was tallying up each player's TPM for each game, I would also put the number of individual possessions that I recorded a debt or credit on for that player. So on my scribbled out TPM sheet, Lonzo Ball's final TPM for a game would read +10 (22) or Corey Brewers would be -9 (8). That indicates that Ball had a +10 TPM in 22 Involved Possessions while Brewer had -9 TPM in 8 Involved Possessions.

*It could also be called Possessions Involved, Play Participation, Involvements, or anything better you can come up with. Not sure I want to stick with IP since when I see it all I think of is Innings Pitched.

In my mind, IP gives you two things.

1) It allows you see how involved a player is in a given game while they are on the court. A high IP means you were highly involved in the outcome of possessions while you were on the court. Two different players might both log 30 minutes, but one gets 25 IP while the other only gets 10 IP. They both spent the same time on the court, but player A was way more involved overall than player B. You could even break it down into Positive Involved Possessions (PIP) and Negative Involved Possessions (NIP) in order to get an even clearer picture of where a player's involvement is.

2) Coupled with TPM and minutes played, it can show how efficient a player was or wasn't with their time on the court. As an example from the data I collected, on Lonzo Ball's record breaking triple double night against the Bucks, Ball recorded a +29 TPM with 32 IP in 39 minutes of play. In the very next game against the Suns, Jordan Clarkson posted an identical +29 TPM in only 16 IP and logging only 26 minutes. Looking at these two side by side tells you a few things. While Ball was way more involved in the Bucks game than Clarkson was in the Suns game, they both logged similar involvement rates (Lonzo had an IP every 49 seconds, Clarkson had an IP every 36 seconds. That's less than possession difference) and Clarkson was way more efficient with his IPs. He had 1.81 TPM/IP while Ball had .9 TPM/IP. This means Clarkson's average IP had a more positive impact on the team than Lonzo's did.

You don't have to like or adopt this little stat, but I thought I'd throw my idea out there to see what mileage it got. I'll still use it since it's become a habitual part of my TPM record keeping.

I look forward to the comment on the SSR postgame so we can get some more Laker fans involved in the discussion. Hopefully by then I will have had enough time to collect all the numbers I have together and make a proper FanPost about the Lakers' TPM. Probably not, but one can dream.