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# Pro Football Reference Blog

## What Does the Season Series Tell Us About Playoff Matchups?

Posted by Neil Paine on January 12, 2011

All four of this weekend's playoff matchups feature rematches of regular-season games:

Rk
1 NWE 2010 2010-12-06 NYJ 13 12 Mon W 45-3
2 NWE 2010 2010-09-19 @ NYJ 2 2 Sun L 14-28
Provided by Pro-Football-Reference.com: View Original Table
Generated 1/12/2011.
Rk
1 PIT 2010 2010-12-05 @ BAL 13 12 Sun W 13-10
2 PIT 2010 2010-10-03 BAL 4 4 Sun L 14-17
Provided by Pro-Football-Reference.com: View Original Table
Generated 1/12/2011.
Rk
1 ATL 2010 2010-11-28 GNB 12 11 Sun W 20-17
Provided by Pro-Football-Reference.com: View Original Table
Generated 1/12/2011.
Rk
1 CHI 2010 2010-10-17 SEA 6 6 Sun L 20-23
Provided by Pro-Football-Reference.com: View Original Table
Generated 1/12/2011.

How much extra information (above & beyond the Simple Rating System) can we glean from these previous matchups of playoff foes?

To answer that question, I looked at every playoff game since 1970 that featured teams who played in the regular season, recording their respective SRS scores and the total HFA-adjusted margin of their previous meetings (the HFA adjustment was -2.7 to the home team's margin and +2.7 to the road team). There were 206 such cases, ranging from the Colts and Dolphins' 1971 AFC title-game showdown to the Eagles-Packers game this past Sunday. Plugging the data into a logistic regression model, we arrive at the following formula:

p(W) ~ 1 / (1 + EXP(-0.1319031*SRSDiff + 0.01757894*TotMOV))

Where SRSDiff = (Home Team SRS - Road Team SRS + 2.7), and TotMOV is the cumulative HFA-adjusted margin of victory for the team in all of its regular-season matchups with the playoff opponent. Both variables were significant at the 0.05 level.

Using this equation, we get the following win expectancies for this weekend's games:

New England vs. NY Jets: 1 / (1 + EXP(-0.1319031*(15.4 - 6.5 + 2.7) + 0.01757894*(-11.3 + 39.3))) = 73.8%

Pittsburgh vs. Baltimore: 1 / (1 + EXP(-0.1319031*(10.2 - 6.4 + 2.7) + 0.01757894*(-5.7 + 5.7))) = 70.2%

Atlanta vs. Green Bay: 1 / (1 + EXP(-0.1319031*(6.1 - 10.9 + 2.7) + 0.01757894*(0.3))) = 43.0%

Chicago vs. Seattle: 1 / (1 + EXP(-0.1319031*(4.1 - (-9.4) + 2.7) + 0.01757894*(-5.7))) = 90.4%