Friday, February 12, 2021

It's About As Difficult to Overcome an 8-0 Deficit in NCAAB (3 scores) as a 7-0 Deficit in NCAAF (1 score)

Starting slowly (and going down by a large margin early) greatly reduces your chances of winning the game - the question is by how much. Having the rest of the game to claw back is generally overvalued - for example, an analysis from Harvard illustrated how in the NBA, winning the first quarter is the most impactful on going on to win the game

The concept of momentum is also greatly overvalued - something I found to be true in both NCAAB and NCAAF. So if momentum isn't real, but getting out to an immediate lead increases your chances of winning the game, then it follows that just banking those points is enough to push your win probability higher, substantially. In other words, your opponent now has to outscore you by the amount they're already losing over the rest of the game.

But where do these deficits intersect for NCAAB and NCAAF? For example, is it harder to come back from a 6-0 deficit in NCAAB or a 14-0 deficit in NCAAF (2 scores in each case)?

I took the data from the above momentum exercises (2016-17 for NCAAB, 5,461 games; 2015 for NCAAF, 687 games) to find out how often a team won when starting the game on a certain run. I then limited the exercise to scores that occurred in > 1% of games.

 NCAAF % Games Held Lead NCAAB % Games Held Lead 3 25.4% 52.3% 1 4.1% 53.1% 7 69.3% 74.0% 2 68.8% 56.6% 10 15.0% 77.9% 3 29.2% 57.4% 14 23.2% 91.9% 4 18.9% 62.3% 17 8.0% 85.5% 5 14.0% 68.4% 20 3.6% 92.0% 6 8.3% 70.4% 21 10.2% 97.1% 8 3.9% 73.5% 24 3.9% 96.3% 10 1.7% 80.9%

Due to the higher volume of possessions per game in college basketball, it is much easier to overcome a larger deficit (i.e. being down 10-0 is being down 4 scores, which would be equivalent to 28-0 in football). NCAAF's slope is much steeper and gets closer to 100% much faster, whereas even a double digit lead only gets you slightly above an 80% win percentage in NCAAB.

An interesting quirk (not shown above): only 5 NCAAF games (0.7%) started out 2-0 on a safety, and the leading team went on to win 4 of these (80%).

But where do these two meet?

 NCAAF, Initial Lead Win % Delta 3 7 10 14 17 20 21 24 NCAAB,InitialLead 1 0.9% -20.8% -24.8% -38.8% -32.3% -38.9% -44.0% -43.2% 2 4.3% -17.4% -21.3% -35.3% -28.8% -35.4% -40.5% -39.7% 3 5.1% -16.6% -20.5% -34.5% -28.1% -34.6% -39.8% -38.9% 4 10.0% -11.7% -15.6% -29.6% -23.1% -29.7% -34.8% -34.0% 5 16.1% -5.6% -9.5% -23.5% -17.0% -23.6% -28.7% -27.9% 6 18.1% -3.6% -7.5% -21.6% -15.1% -21.7% -26.8% -26.0% 8 21.2% -0.5% -4.4% -18.4% -12.0% -18.5% -23.7% -22.8% 10 28.6% 6.9% 3.0% -11.1% -4.6% -11.2% -16.3% -15.5%

The closet win percentage that matches in each sport is around 74%, which is equivalent to an 8-0 lead in NCAAB (3 scores) and a 7-0 lead in NCAAF (1 score).

Outside of a 3-0 lead in college football, almost every other lead is safer on the gridiron (7-0 and above) than any counterpart in college basketball.