Back in the early days of the 2019 season, we did a post about the effect of the shot clock on two key metrics: goals/gm and shots/gm. The thinking was that the shot clock would likely increase the number of shots taken per game because possessions would be shorter. We also figured that overall efficiency would go down because teams were faced with that hard time constraint.

They key question was whether the decrease in efficiency would be enough to offset the increase in shots. Put another way: would the new rules have a positive or negative impact on goals scored?

Well, we are a year into the shot clock era, and we have some initial numbers to share. Let’s start where we started last time: shots.

Let ‘er rip

In case you snoozed through the past 3 months, the shot clock rule was mostly in reference to a physical shot clock that reset on change of possession or on a shot that was saved or hit the pipe. Offenses had 80 seconds to get a shot off.

Since many possessions used to dawdle on past 80 seconds, we knew that there would be more possessions on a per-60 minute basis this year. And we figured that would lead to an increase in the number of shots per game.

Unsurprisingly, this is what ended up happening.

Year	Shots / 60 min
2013	72.7
2014	71.5
2015	70.6
2016	69.7
2017	70.0
2018	69.8
2019	79.1

2019 saw a rather large increase in the number of shots taken per game, up nearly 14% from 2018. To the extent that the rule change was driven by a desire for more action, this suggests that it was successful.

More is not always better

Of course, more shots could just mean that there were more situations where an offense, staring down a shot clock violation, took whatever shot they could come up with. That may or may not actually increase scoring.

And that was really the central question with the shot-clock: would it increase goals or would it create faster, but sloppier, lacrosse?

Year	Goals / 60 min
2013	20.5
2014	20.2
2015	20.4
2016	20.1
2017	20.7
2018	20.6
2019	22.8

As you can see, offenses took advantage of the shorter clock. While efficiency did go down (27.1% this year vs 28.5% in 2018), the overall number of goals went up this year by almost 11%.

So yes, somewhat misleading section title; in this case, more was better.

What about possessions

Year	Poss / 60 min
2013	75.7
2014	73.3
2015	72.4
2016	72.6
2017	73.9
2018	72.1
2019	84.2

For the purposes of my earlier post, I more or less lumped possessions in with shots, so I didn’t split them out individually. But there is no reason that possessions and shots need to rise in tandem.

Interestingly, the number of possessions saw the largest year-on-year rise of any of these three metrics. 2019 saw nearly 17% more possessions per game than 2018 did.

If you recall, there were 14% more shots this year, so possessions actually increased faster than shots did. This suggests that either A) pointless possession shots went by the wayside or B) there were more possessions this year without a shot.

I suspect it was the latter because turnovers increased nearly 25% this year. We will get into it in later posts, but some teams handled the 80-second-wall better than others.

This is probably the key point behind the idea that while goals did go up, it’s not like the offensive units took the new rule completely in stride.

Let those horses run

I will have more detail on this topic, but in general, our work has shown that an offense suffers when it is artificially slowed down. Whether it is conservative coaching, a desire to maintain possession, or just wanting to rest your defense, there are a range of reasons that you might encourage an offense to be patient.

But by and large, that results in less efficient offense. Which led to the idea that by removing the ability to artificially slow an offense beyond it’s natural pace, the shot clock would be likely to help offense more than defense.

The goal figures above suggest that this theory is plausible.

The 30-thousand foot view

This post was all about filling in the blanks on our early-season post. It’s the 30-thousand foot view of the shot clock’s impact.

But we also have a full year of data about how each team stood up to the new rules. We did some preliminary work earlier in the year about how team’s offensive profile changed under the new rules.

I’ll probably spend some time flushing out a new post on that topic next. Stay tuned…