Counting the Baskets

The Upside Down Celtics

 

Over at the Nylon Calculus, I noted that the Celtics have sometimes been accused of having an upside down line up, in the sense that the back court players can't shoot and the front court players can't play defense. In that post I was looking at a study using a stabilized version of plus/minus data called RAPM that indicated that, while the traditional stereotype was in some ways true there may be an important caveat.

To put it succinctly, guards, on average, contribute more on offense and less on defense,while for centers and power forwards the opposite was true. But the interesting bit is that the spread between the best and worst center on defense and the spread between the best and worst point guard was largely the same.  

If guards really weren't important to defense we would expect the spread between the best and worst point guard to be much much smaller than for centers since it wouldn't matter, for example, if Aaron Brooks, ones of the worst PG defenders or Chris Paul, one of the best, was on the court.  The RAPM data and a more complicated version that combines box score data called Real Plus Minus (RPM), via ESPN, indicate otherwise.

So, in theory, this data indicates that it wouldn't necessarily be bad that the Celtics were  'upside down' on defense.  One would always prefer to have five good defenders on the court and five good offensive players, of course, but it is not inherently less valuable to have an elite defensive guard replace an average guard than an elite center replace an average center.

Focusing on the defense, I put this table together with the defensive RPM scores of the Celtics' current roster, excluding the rookies.  It has each player's raw D-RPM, then adjusted for position and their percentile rank for their position.

 

So, how upside down is this roster?  Outside of Olynyk and Bradley, and perhaps Marcus Smart who projects very well as defender, the Celtics roster is actually not all that upside down.

Based solely on raw D-RPM one would be lead to believe that Joel Anthony, Jared Sullinger, and Tyler Zeller were the C's best defenders, after Gerald Wallace.  However, Sullinger, Anthony, and Zeller are all just average for the their position, indicating they're adequately filling their defensive role but not little more.  

Based on the Position Adjusted column, however, the clear difference makers on defense for the Celtics were Gerald Wallace and Avery Bradley, both of whom are above the 90th percentile and rate 2.4 points per 100 possessions over position average on defense. (Side note, Bradley is listed as a point guard by ESPN, despite manifestly NOT being a point, though for defensive purposes guards are ranked together here as there was no significant difference on defense).

On the other side, while Rajon Rondo and Kelly Olynyk both rate near the bottom on raw scores. Rondo, despite his reputation, scores a little below average for his position,but Olynyk is much much worse when position is taken into account.  A little of that can be attributed to listing Olynyk as a center, where his more natural position is power forward, but he would still be last on the team by a wide margin.  

Olynyk scores poorly on Rim Protection using SportVu data, allowing opponents to shoot well above average on contested shots near the basket for a big man at 54.6% (average being 50%). But, the team as whole faired no worse protecting the rim with Olynyk on the court, according to NBAWOWY data.  However, Olynyk fouled too often when he did try to protect the rim, a stat that shows up in even the raw on/off data for the team, with the free throw rate jumping from 28% to 32% for opponents when Olynyk was on the court.

Olynyk as a big man that can shoot from outside and pass, has the potential to be the Celtics most complete offensive player, but in order to impact the game positively he will need to learn passable defense.

This is the part of the post where I add the caveats and disclaimers about RPM as a stand alone metric.  It is not perfect, with a single year there are multi-co-linearity issues, which adds to noise.  There are always factors on defense that emerge from the combination of players that can't be completely isolated to individuals.  But RPM does have a decent track record, with its predecessor xRAPM, in terms of prediction.

Like any metric or stat we expect some reversion to the mean next year, adding to that an aging factor, the safest predictions are that Olynyk's defense will improve and that Bradley's and Wallace's, especially, will get worse.  Making the defense that much less upside down, though not that much better.

Passing Efficiency on the Celtics

(Avery Bradley is Still not a Point Guard and an optimistic note on Evan Turner)

Over at the Nylon Calculus, I unveiled a little exploratory analysis I had been dong with SportVu data compariing those stats with offensive efficiency as measured by a stablized plus-minus system for offense called O-RAPM.  The SportVu measure that looked like the largest contributor was a measure of passing efficiency that divided the assists, hockey assists and free throw assists by the number of passes the player made, first developed by Nick Neuteufel and Aqeel Phillips.

In that vein, I thought I would increase my research efficiency a little by taking a look at how Passing Efficiency measure applies to the current prospective Celtics line up.  Sure, it's August, the NBA is in full off season mode, and the Celtics have a roster that feels likely to change.  But, there are no guarantees that it will change significantly.  Plus, applying the new measure to a prospective roster helps put it in context and often helps me understand the measure better.

The first thing of note that came out of the analysis for Celtics fans, is that Rajon Rondo is indeed an efficient passer as well as being a ball dominant passer.  Rondo rated as the 18th most efficient passer in the league last year but had the highest Passing Impact in the league due to how many passes he threw per 100 possessions, passes per one hundred possessions was also positively correlated to offensive efficiency in the study.

Applying the coefficients from the study to both Passing Efficiency and Passes per Possession, I came up with an estimate of Passing Impact, which is the estimated plus/minus of each player's passing on offense. [1. Measure is calibrated so that every player's Passing Impact is positive outside of turn overs, which was a separate measure in the study]

Below are the three passing measures applied to the Celtics on the current roster other than the incoming rookies and Chris Babb who didn't play enough possessions to be included in the study.

To put some perspective on the numbers here, the Passing Efficiency average of players in the study was .097.  In other words, for the average player just under 10% of passes lead to an assist of some kind.  The number of passes per player was 71, though that varied greatly by position.

• Not surprising that Rondo and Phil Pressey land in the top spots.
• Evan Turner comes in third, one thing to watch here is that Turner played in the Sixers' very fast paced, if sloppy, offense.  There may be some dual causation in the measure with pace, so we'll have to see if he maintains that kind of Passing Efficiency in a new system.
• Avery Bradley IS NOT A POINT GUARD!!!!!!!! He might look like one, he might on the small side and quick, but, no, he is NOT A POINT GUARD!!!!!
• Marcus Thornton had decent efficiency but was an infrequent passer, showing how much he played off of the ball.
• Kelly Olynyk had good Passing Efficiency for his position.

Position Adjustments

Passing Efficiency, like assists, is highly correlated to position, as is Passing Impact.  Here's the table with averages by position:

 

Using those we can adjust the roster numbers based the level of Passing Efficiency typical of the position, via Basketball Reference, except for Bradley who I changed to a two guard, see above! Any player with a position adjusted rating above one rates as above average for their position, anyone below one is below average for their position:

• Turner comes in as rated the highest over his position of anyone on the prospective roster.  If we considered him a two guard, where he played part of his minutes last year, he would still rate as above average.  Turner's more traditional distribution metrics assist to turn over ratio only rate him as average, possibly showing the influence of the fast but chaotic Philly offense with the worst turnover rate in the league.
• Olynyk is second in position adjusted passing efficiency, though listed as a center.
• Rondo comes in third in the much tougher point guard spot.
• Bradley, even as a shooting guard has well below average passing efficiency.
• Jared Sullinger is just a bit above average.

There has been some discussion over at Celtics blog on building a roster around a non-shooting point guard as Rondo is reputed to be, and whether or not, in fact, Rondo actually deserves that reputation.  I come down on the side that his reputation may be slightly over done, but there's no escaping that he's been a below average shooter from distance and improved mid-range shooting is only a partial salve to the line up spacing problems.

The answer to building around Rondo's shooting, if the Celtics decide to do that, is, of course, to surround him with shooting.

It's a little less clear what the synergies are with passing, and at this point there probably isn't sufficient data to do much with line up analysis, at least using the SportVu measures.  That said, my starting assumption is that having additional play making on the court doesn't crowd out the efficacy of the point guard's passing.

At this point, I want to bring in the more traditional assist measurements, in this case assists per 100 possessions and assist to turnover ratio.  Both are fairly well correlated to Pass Efficiency, though there may be some diminishing returns for both.

We can also bring in the rookies, Marcus Smart and James Young using their college numbers via Draft Express.  Smart had 5.5 assist per 40 minutes pace adjusted, approximately 7.6 per 100 possessions, and an assist/turn over ratio of 1.78.  Young had 2.1 assists per 40 minutes, just under 3.0 assists per 100 possessions, and an assist to turnover ratio of .89. I am somewhat more encouraged by Young's good assist numbers than discouraged by his meh asst/tov ratio given his age.

If we look at a possible Zeller-Bass-Green-Bradley-Rondo starting line up, that is four average to below average playmakers on the court with Rondo, with no real secondary play maker.  One also would have a fairly lackluster rebounding front court.  Even without roster moves, I think that either Sullinger or Olynyk end up getting the starting nod over Bass or Zeller. 

The issue with the Celtics roster, as one would expect without real stars, except, perhaps Rondo, is that they don't have any complete offensive players.  The shooting guards have limited playmaking skills, the one decent shooting wing, Green, also has limited playmaking abilities.  Meanwhile the better playmaking wings aren't shooters.  The closest players the Celtics have to complete offensive players are Olynyk or Sullinger, if Sullinger's outside shot starts to fall.

Here's hoping Olynyk, Sullinger or Smart have break out years.

So Evan Turner...

This post originally appeared on the Nylon Calculus on 7/23/2014. Re-posted here to keep all of my Celtics posts together.  

Also see my other posts there on the Value of Free Throws and the Spurs Draft Prowess.

The Celtics seem to have signed Evan Turner as a free agent, probably not the number two pick most of the tank commanders were hoping for at the beginning of last year.

Reports are that this is just part of the mid-level exception, and likely a short term contract, so the money is not a concern. But the Turner signing brings the Celtics to 15 players with guaranteed money and that much closer to the tax line, limiting some flexibility and squeezing out the three non-guaranteed players under contract, most notably Christapher Johnson.

It is hard to tell at this point whether the Turner signing makes further trades more or less likely. On the one hand, as I noted, roster and financial flexibility are somewhat more restricted, on the other hand the roster may make even less sense than it did, so trades seem more likely. Given that, I decided to take a look at Turner in the context of the current Celtics lineup, to see how he might or might not fit, which can also shed light on the trade question.

Turner can play either shooting guard or small forward. Last year according to 82 Games, Turner played almost 75% of his minutes as a small forward, while his Indiana playing time was more evenly split. On this current roster I think Turner probably gets more time at small forward, especially if they are serious about playing Marcus Smart off the ball.

Here is how Turner compares to the Celtics' current small forwards using some of the advanced overall metrics, color formatted to show the relative strength:

Essentially the 31 year old Gerald Wallace is the only one to rate as above average in any of the metrics — Win Produced and RPM. Otherwise it isn't pretty and Turner is pulling out a lot of red, even in that group. So, the overalls on Turner aren't good last year, nor were they much better in previous seasons.

But, let's brave some of the finer grained numbers to see what kind of a game Turner has, or maybe could have. Turner tends to be a ball-dominant wing, which shows up in his distribution numbers. He got both more assists and had more turnovers than the other current small forwards on the Celtics roster.  His overall assist-to-turnover ratio is approximately average for a small forward, if we're generous.[1. Per Basketball Reference player comparison]

Both Green and Johnson tend to play off the ball more than Turner or Wallace. Turner looks like an adequate secondary ball handler.

I have been re-working a cluster analysis of players by their shot selection types that I ran last year using the unfortunately now shut down HoopData site, this time using NBA.com data (which one expects to be around for a while). The final analysis is still a ways off, but both in the prior analysis and the new version Turner rated as a 'Slash' wing relying more on driving or cutting to the rim than the three pointer. Unfortunately, he too often settled for pull-up mid-range shots when he was cut off from the basket, putting him in a possible third category of Mid Range shooters. As seen in this shot chart created by Austin Clemens:

Looking at the chart, not only is there too much blue, but too much below-average shooting in below-average places. There is a similar pattern viewing his shooting in tabular data along with the other Celtics small forwards the pattern is just as clear[2. Ibid.]:

The funny thing is that Turner actually shot fewer mid-range shots last year than any previous year. Unfortunately, progress has been slow and mostly offset by a fall in his conversions at the rim. His free throw rate is also poor for a Slashing guard, though that too had a slight uptick, especially in his Indiana stint.

Obviously there's an argument for the mid-range game if a player is good at those shots like Dirk Nowitski. Turner is not, see above.

By the way, it is also clear looking at this that Chris Johnson fills a different role offensively than the other wings on the roster.  He is the only true stretch player and one that mostly plays off of the ball.

In the other stats, Turner is a good rebounder for his position, though mostly in less valuable defensive rebounds, barely registers on blocks and is below average on steals.

The argument has been made that the Celtics might expect Brad Stevens to transform Turner into an asset the way he did with Jordan Crawford last year. That doesn't really seem like the best use of Steven's time given the two first round picks on this roster and Kelly Olynyk and Jared Sullinger still in need of development.

It's hard to see the precise role Turner could fill on this roster even with improvement other than secondary ball handler off the bench, which makes more moves feel all the more likely.