"Time and Score!" (HV Weekly: 5/22/2020)
Analysis around situational shot selection + a new deep dive video on defensive concepts.
Welcome back to the Hoop Vision Weekly!
Lately, the support for Hoop Vision and this weekly newsletter has been incredible, and wildly appreciated. We keep breaking records this off-season; despite no live basketball, our last two Friday editions are the two most-viewed newsletters since we got this thing started in December 2018. Here’s hoping for three in a row!
Thank you to everyone sharing and subscribing — more coming throughout the entire summer!
In today’s edition:
New video on defensive concepts
The nuance and context around shot selection, with some new analysis built upon play-by-play data
Quantifying late-game behavior
What to expect this week on HV+
Should You Help One Pass Away on Defense?
Earlier this week, we released a new 12-minute voiceover video on YouTube.
The video starts with Game 6 of the 1998 NBA Finals — in which the Bulls were called for three illegal defenses in the first quarter alone — and then looks at how defensive philosophy has shifted with the change in rules and rise of spread offenses.
Video topics include:
The 1998 NBA Finals and the old illegal defense rules
Tom Thibodeau’s defense — loading to the ball and ice
No-Middle defenses (Texas Tech and Baylor)
Pack Line defenses (San Diego State, Wisconsin, Virginia)
Help-Only-When-Necessary defenses (Michigan and Saint Mary’s)
How the rise of three-point shooting has changed defensive philosophy
How a lead changes shot selection
Shot selection is a staple of basketball that is typically discussed at face value, and rarely analyzed with the nuance and perspective of other topics which drive the game we all enjoy so dearly.
Earlier this week on Twitter, I posted this table on win percentage and shot selection:
Last season, the team that shot more threes (3PA/FGA) within an individual game won 48.2% of the time. As you can see, that win percentage number has generally increased over the last 15 seasons.
For several reasons, this type of analysis is fairly limited. One glaring issue — pointed out by Seth Partnow — is that the context of a game (score and time remaining) can change strategy and behavior.
Let’s switch gears and look at football as an example; it’s the sport where this line of decision-making is abundantly clear and widely accepted.
When a team takes a big lead into the second half of a football game, they have an incentive to run the ball and keep the clock moving. From a statistical perspective, the winning team is going to end up with inflated rushing stats due to that change in incentive — even if running the ball wasn’t what actually built that lead in the first place.
In basketball, the most obvious situation we see with a similar effect is late-game fouling. Just like a late-game lead will likely pave the way for more running plays on a football field, a late-game lead likely will lead to more free throw opportunities on a basketball court.
Intuitively, there are reasons to believe shot selection and three-point shooting could be prone to a similar effect.
A team trailing by a wide margin late in a game has more incentive to start taking more three-pointers; this type of ”let it fly” approach increases scoring variability and decreases average possession length. A team winning by a wide margin has the opposite incentives — they will run their offense patiently and milk the shot clock.
We also have found in the past — “Psychology of the Hot Hand” — that shot selection is altered based on the context of the game. When a player hits a three, for example, his next shot is more likely to ALSO be a three.
Jumping back into the initial tweet with the yearly table, I scraped play-by-play data from every team in the top six conferences — including their non-conference games.
The takeaway from this is pretty obvious, right? Immediately, we see that three-point rate skyrockets in the last minute of the game.
Interestingly, three-point rate is at its lowest to start the second half — a finding that puzzled me.
After some thought, the best explanation I could wrestle up is that coaches often tell their teams to “stop settling” for jump shots during halftime talks; this may change behavior in the opening minutes. That’s purely speculative and anecdotal, however, so please feel free to send us a reply if you have a better idea.
For comparison’s sake, the graph below shows free throw rate instead of three-point rate:
For free throw rate, the increase is much more consistent over the course of each half — ending in a similar skyrocket in the final minute. Naturally, as teams approach the team foul limit/bonus, free throw rate increases.
To parse through the data further, we need to isolate the winning team from the losing team. The late-game behavior of a team with the lead is much different than the late-game behavior of a team playing from behind.
The graph below is again three-point rate, but this time points have been added for the winning team and losing team at that particularly point in the game.
Now we can really begin to see late-game effects.
The team with the lead (represented by red dots) take more threes than their opponents in the first half. In the second half, the opposite is true — particularly after the 10 minute mark.
The graph provides some evidence that my initial tweet was misguided, but we can use the play-by-play data again to see just how misguided.
(Note: The play-by-play data is from games with at least one team from a top six conference. The original tweet was from all DI vs DI games.)
The team that shot more threes (3PA/FGA) in the…
First 10 minutes of the game won 53.2% of the time
First 20 minutes of the game won 53.1% of the time
First 30 minutes of the game won 52.8% of the time
Full 40 minutes of the game won 48.8% of the time
Next week for HV+ subscribers
We will be releasing a final small batch of teams from our (cancelled) NCAA Tournament scouting breakdowns. If you missed them previously, the Duke Scouting Breakdown is unlocked for everyone to read and the other 39 teams are available for HV+ subscribers by clicking/tapping here.
We will be sending out a video/tutorial on the Defensive Accounting Report we used at New Mexico State. The tutorial will include how we incorporated the report it into our video workflow, a real example of generating the report, and more thoughts on quantifying individual defense.
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