Fun Graphs

[Fan from VT]

Some fun graphs I made relating stats to other stats. Most are league wide trends. Ask questions, debate, etc.

[Fan from VT]

To clarify some random things:

R^2 values show how tight an estimated line of best fit correlates to the actual data. 1.0 means 100% tight. 0 is data points all over the place. Closer to 1.0 means a more accurate predictor of whatever is being measured. So for example, Graph 2 shows that True Shooting is more tightly related to Offensive Efficiency than to overall wins. Which should be obvious, because TS highly impacts offense, but offense is only half the discussion in terms of winning, so it's good that it fits.

TO refers to Turnover Ratio (not raw total turnovers)

OffEff is Offensive efficiency (points per 100 possessions)

DefEff is Defensive efficiency (points allwoed per 100 possessions)

PtDiff is Point Differential Per Game

OReb is the Offensive Rebounding Rate (not raw offensive rebounds)

OffEff-DefEff is the Offensive Efficiency minus Defensive Efficiency, a tight surrogate for Point Differential

[Fan from VT]

The other thing I noticed and don't really have enough time/skills to deal with was trying to do more in depth year to year analysis. I found it seemed best to use a team's rank in a given category rather than the absolute value (for example, how a team ranked in TS vs using the actual TS each year). I believe this was the case because TS/OffEff/DefEff etc. all vary year to year league wide so a team could maintain the same TS in an absolute sense but move up or down relative to other teams (and since it's a competitive sport, relative to other teams is all that matters). I think this variance is likely due to year to year differences in rules, call emphasis, refing, lockouts, etc. So rank seemed more accurate, because by absolute value your TS might stay the same and show "no improvement," but if everyone elses TS generally trended down because that was a year they allowed more contact or something, then you should actually get credit for maintaining the same TS in the face of a league decrease, and using rank value covers that.

[billysan]

Not sure about anyone else, but that first graph shows me we really have sucked at rebounding.

[Fan from VT]

This first graph is the Celtics' rank in various categories in the league as trending year to year.

(I should point out, I did make a mistake in labeling.
The "Point Differential" is actually their true Point Differential, not their rank. So bigger (further below the upper x-axis) would be better. So as their offense has gotten relatively worse, their point differential has diminished, trending toward zero from their elite '07-'08 season.)

Their Defense clearly has been elite over that time, and interestingly enough has remained so despite the dropoff in defensive rebounding.

Their rebounding has gone from average-good overall (good to very good on defense, average offense) to just bad (terrible offense, average defense).

Their TS% has been very good during the KG era, though dipped recently.

Offense has been average to quite good, but really has fallen off.

Basically, some of this information is a little pessimistic.
-Both rebounds trending down.
-Offense trending down significantly
-Turnovers bad, staying there
-TS trending down a little
-Point differential (best predictor of future wins) consistently trending down.

So all together, the question is are the C's clinging to relevance by maintining elite D despite across the board declines in all else? And are those declines harbingers of team-wide diminishing skills/athleticism that will eventually affect D as well? Will all those diminished areas catch up with them and make the C's average? Did their offseason moves change the trajectory of these trends?

[Fan from VT]

Not sure about anyone else, but that first graph shows me we really have sucked at rebounding.

Yes, basically, they have.

I think it's concerning. I believe it is a major component of their offensive dropoff (extensive debate on front page), though their TS dropoff is also contributory, for sure.

My concern is that universally decreasing rebounds, decreasing offensive efficiency, and decreasing point differential represent a general decline in overall skill of the C's; if their elite defense becomes affected, they will be a much worse team. Hopefully their offseason moves are enough to mitigate that.

[billysan]

Not sure about anyone else, but that first graph shows me we really have sucked at rebounding.

Yes, basically, they have.

I think it's concerning. I believe it is a major component of their offensive dropoff (extensive debate on front page), though their TS dropoff is also contributory, for sure.

My concern is that universally decreasing rebounds, decreasing offensive efficiency, and decreasing point differential represent a general decline in overall skill of the C's; if their elite defense becomes affected, they will be a much worse team. Hopefully their offseason moves are enough to mitigate that.

Yeah, for me it's all about possessions. A missed defensive rebound is almost like a turnover while an offensive rebound is like a steal. The greater number of chances to score (ball in possession) the more points possible.

Defensive rebounding also has a big time effect on overall defensive performance. The same principle applies because the less chances you give to score, the less points you give up on average.

[Celtics18]

Not sure about anyone else, but that first graph shows me we really have sucked at rebounding.

Yes, basically, they have.

I think it's concerning. I believe it is a major component of their offensive dropoff (extensive debate on front page), though their TS dropoff is also contributory, for sure.

My concern is that universally decreasing rebounds, decreasing offensive efficiency, and decreasing point differential represent a general decline in overall skill of the C's; if their elite defense becomes affected, they will be a much worse team. Hopefully their offseason moves are enough to mitigate that.

I think that the off-season moves have a good chance to mitigate some of the drop off in important statistics from last season.  I don't have the ability to make fancy charts for this, but I'll at least make the hypothesis, based on browsing through 82 games' 5 man unit numbers, that the 2011-2012 Celtics suffered more than any other elite team in the league when forced to go to the reserves.  Basically, the starting unit, which is still in tact, was very, very good, and the bench was fairly abysmal.


I think there's very strong reason to believe that the additions of the likes of Jason Terry, Courtney Lee, Jeff Green, Jared Sullinger, and Darko Milicic will amount to a significant improvement over last year's second unit.  I expect the overall team numbers to reflect the improvement.

[Fan from VT]

Graph 2:




This one was I was interested how a team's True Shooting related to other measures.

Not surprisingly, there was a strong positive association between True Shooting and Offensive Efficiency.

There was also a positive correlation, though not as strong, between TS and Point Differential and Wins. This nicely backs up the intuitive thought that TS would greatly impact offense, and that a good offense helps win games, but is not a super strong connection because defense is not considered.

[Fan from VT]

Graph 3 was fun visually. It really shows how league-wide Point Differential really mirrors actual wins, furthering the idea that point diff is generally a more accurate evaluation of a team's "Goodness" going forward.

This one also shows that the difference between a team's offensive and defensive efficiency is a very tight surrogate for team's actual point diff. This was nice to confirm so that you can predict how many wins a team would improve by just by adjusting only offensive or defensive efficiency.

[Fan from VT]

Graph 4 simply confirms the findings of graph 3 more linearly represented, showing that as a team's Offensive Efficiency minus Defensive Efficiency increases, so do a team's Wins and Actual Point Differential. The correlation with Point Diff is just about as tight as you can get (>.99), and also very nicely tight with actual wins (>.91).

This is useful when thinking about how a team is going to get more wins, you can look at how much you would need to adjust your offensive efficiency or defensive efficiency to get "x" more wins.

[Fan from VT]

Improved Graph 1.

-Now shows Point Diff as a league rank, showing the decreasing trend.

-Also added rank in Wins, showing the decreasing place in the standings each season.

-Note: Difficult to see both Point Diff and Wins, as the C's league rank in these two categories (not surprisingly, they are tightly correlated) were identical for most seasons.

[GranTur]

These graphs are too small to read.

[Fan from VT]

These graphs are too small to read.

True, sorry about that. It's an artifact of the only way I know how to get them here.

You can Right Click and Open In New Tab and they zoom in a bit.

[Fan from VT]

Graphs 5+6 were looking at shooting efficiency and trying to correlate those with wins. I used the two more common measures of shooting efficiency, eFG and TS. I found that both were (not surprisingly) fairly strongly related to overall offensive efficiency, but not perfectly. TS was SLIGHTLY more closely correlated, but probably not by a meaningful amount (.74 vs 73).