Not all free throws are created equal anymore … at the G-League

Yesterday the G-league announced that it will experiment with a new free throw rule in order to reduce the duration of the game. In particular, instead of awarding one, two or three free throws depending on the violation, it will award one free throw that will be worth one, two or three points respectively. Many interesting things came to my mind when I first heard that. For example, teams sometimes attempt to ice the shooter for their second free throw shot by taking a time-out. And it seems to work.  Not anymore though!

There is also a difference in the FT% with regards to the splits. Following are the percentages from last season over the whole league:

As we can see there are some differences (statistically significant as well) between consecutive free throws in a FT trip. Others have noticed similar behavior. Furthermore, we see that overall the FTs at a 3-point shooting foul have higher percentage since most probably the players that are awarded these fouls are better shooters. With the new rule change the unit of interest is the FT trip. Last year there were on average around 3 trips for 1 FT, 10 trips for 2 FTs and 0.4 trips for a triplet of FTs per team per game. Now all of these trips will be awarded a single FT that will be worth 1, 2 or 3 points respectively. What will be the impact on scoring? Assuming (and this is a big assumption that I will expand a bit on later) that teams keep getting the same type of FT trips and have the same percentages (the ones that matter here are the percentages of the first FT of the trip), the following figure shows the expected number of points per game per team from FTs compared with what they get now:

As we can see almost all teams are expected to get less points from the charity line if this rule was to be introduced in the NBA. The degree of reduction depends on many factors (type of trips for a team, actual FT%, degree of FT split percentages etc.). However we could start looking at pairs of teams and examine who would get a benefit in their matchup. For example, Memphis is barely expected to see any decrease in its expected points from FTs, but Brooklyn will see a decrease almost equal to 1 point. So in a matchup between BKN and MEM the new rule would give Memphis an 1 point advantage.

Of course here come the assumptions. The rule change is going to change the way teams foul (I think) and hence, who and what kind of trips a team gets. How? I don’t know. But now you can imagine a league-average player (even including the splits) currently has around 6% chance of not scoring from a pair of FTs. With the new rule he will have a 25% of not scoring. This can make Euro fouls a thing again. Of course, someone will point that there is also a 75% chance of scoring 2 points as compared to the 56% chance of that happening today with the current NBA rule. True; that’s why I said I don’t know how this will change the fouling behavior. Moreover, teams might put more emphasis on practicing FTs (which I would believe and hope do anyway but even more so now) – not to mention personnel movement. What is clear though, is that with the current levels of FT% the teams are expected to score less from the line. Scoring is another variable on fan satisfaction (as is the duration of the game). Of course the reduction will be less than 2 points per game but fans do like more points (maybe not from the FT line anyway). Also we have not separated the rule for the last 2 minutes – that will be the same as is now – so this will further reduce this impact on scoring (it might also bring an uptick of fouls just before the last two minutes so teams can benefit from the increased variance from the new rule — but we cannot know until we see).

We will see how things will go in the G league this season but it is certainly an intriguing change.