NBA Playoffs 1991-2022: ATS Win Percentage of SU Winner; Average Line Differential

by Al McMordie

In Game 2 of the 2022 NBA Finals, the Golden State Warriors blew out the Boston Celtics, 107-88.  The key was to the victory was the Warriors’ 35-14 advantage in the third quarter.  And that was the 91st different quarter in these 2022 Playoffs where one team had a double-digit margin over the other.  That’s the all-time record for such blowout quarters, exceeding the previous high of 90 quarters in the 2017 playoffs.  The upshot of this is that we've seen a whole host of blowout games, and this NBA Playoffs is likely to set the record for the largest average point spread differential for its games (dating back to 1991).  Not surprisingly, we've had very few hotly-contested games.  And the straight-up winner has covered the spread in a relatively-high percentage of games.  The past two seasons have two of the four-highest ATS win percentages (for the SU winner) in the last 32 Playoff seasons (the 2021 season saw the SU winner go 81-4 ATS, for a 95.2% ATS record - the all-time high).

To put this current season in an historical perspective, let's review the data from 1991 to 2022 (the 2022 data goes through June 5). -- Editor's note:  this data has now been updated to go through the end of the 2021-22 season, on June 16.

NBA Playoffs, Year by Year ATS record of the team which won straight-up.
And the average point spread differential of each playoff game.

1991:  54-12-2, 81.8%, avg LD 9.25
1992: 57-14-2, 80.2%, avg LD 8.56
1993:  61-14-1, 81.3%, avg LD 7.89
1994:  63-14-0, 81.8%, avg LD 7.59
1995:  59-12-2, 83.0%, avg LD 10.28
1996:  52-16-0, 76.4%, avg LD, 9.97
1997: 52-18-2, 74.2%, avg LD, 8.02
1998: 57-13-1, 81.4%, avg LD, 9.14
1999: 54-12-0, 81.8%, avg LD, 9.50
2000:  57-15-3, 79.1%, avg LD, 8.77
2001:  59-10-2, 85.5%, avg LD, 9.69
2002:  50-19-2, 72.4%, avg LD, 8.13
2003: 75-11-2, 87.2%, avg LD, 9.02
2004:  62-17-3, 78.4%, avg LD, 8.09
2005: 75-8-1, 90.3%, avg LD, 9.62
2006:  70-16-3, 81.3%, avg LD, 9.28
2007:  61-14-4, 81.3%, avg LD 8.29
2008:  71-13-2, 84.5%, avg LD, 10.27
2009:  67-16-2, 80.7%, avg LD 10.42
2010:  74-7-1, 91.3%, avg LD 10.06
2011:  64-13-4, 83.1%, avg LD 8.46
2012:  66-15-3, 81.4%, avg LD 7.58
2013: 72-13, 84.7%, avg LD, 9.93
2014:  73-14-2, 83.9%, avg LD, 9.76
2015:  66-14-1, 82.5%, avg LD, 9.79
2016:  75-11, 87.2%, avg LD, 11.52
2017:  62-16-1, 79.4%, avg LD, 10.74
2018:  70-12, 85.3%, avg LD, 10.57
2019:  71-10-1, 87.6%, avg LD, 10.05
2020:  70-10-3, 87.5%, avg LD, 9.93
2021:  81-4, 95.2%, avg LD, 11.21
2022:  78-9, 89.6%, avg LD 11.89

The average LD in Playoffs, 1991-2022, is 9.51
The SU winner in a Playoff game has gone 2078-412-50, 83.4% ATS

This past regular season (2021-22), the average line differential was 10.62.
In the 2020-21 regular season, the average line differential was 10.70.

Indeed, the past two regular seasons have seen a big jump in this metric.  Historically, in the regular season, from 1990-91 to 2021-22 the average line differential was just 9.19.  And the past two post-seasons rank among the top 3 Playoffs (along with 2016) with the greatest line differentials.

What immediately jumps out is how the points of an NBA point spread are becoming less "valuable."  And, of course, this has implications for teaser bets.  Say, for example, a sportsbook offers odds of -120 on a 2-team, 5-point NBA teaser.  That would have a much different value in 2022, when the average game in the regular season fell 10.62 points away from the point spread than even just a few years ago.

Of course, based on this data, one should also consider the (negative) implications of buying half-points.  And given the relatively few times (13 of 168 the past two post-seasons) a Playoff game has resulted in an underdog losing SU, but covering the point spread, one may want to consider -- if one likes the underdog -- taking it on the moneyline rather than the point spread.

Good luck, as always...
Al McMordie

All photographic images used for editorial content have been licensed from the Associated Press.

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