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The Tale of MLB's Post-Season Two Leagues

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Remember all those big favorites that made their way into MLB’s postseason? The record-breaking four 100+ win teams from the regular season? The difference of 20 wins between the best and worst seeds in each league? The theoretical advantage of a first-round goodbye for top teams under MLB’s new playoff system?

It seems like there’s only one league of note this season about the big gap between baseball’s rich and poor.

Chaos reigned in the National League. After the bottom rows won both wildcards, the San Diego Padres and Philadelphia Phillies continued that energy in the divisional round, knocking out the heavily favored Los Angeles Dodgers and Atlanta Braves, respectively. Whether through the lens of regular season win-loss records, look at the magnitude of these upsets – the losers of both series outpaced their opponents by more than 85 points – or our pre-series Elo ratings, the Padres and Phillies, were pulled. Here are two of the biggest episode series shockers since the round started in 1995:

Two ways to gauge the division tour’s biggest woes

Biggest gaps in regular season win percentage and Elo rating between underdog and favorite in MLB division series, 1995-2022

Year winning Incompetent Openness Year winning Incompetent Openness
2022 SDP LAD -.136 2022 SDP LAD -82.1
2020 HOU OAK -.117 2001 NYY OAK -77.6
2022 PHI ATL -.086 2002 MIN OAK -67.8
2008 LAD PRC -.084 2003 PRC ATL -54.3
2003 PRC ATL -.080 1998 SDP HOU -52.6
2019 WSN LAD -.080 2021 EMPTY TBD -51.8
2011 STL PHI -.074 1996 HONEY CLE -48.9
1996 HONEY CLE -.072 2022 PHI ATL -48.7
2017 NYY CLE -.068 1997 CLE NYY -43.5
2012 STL WSN -.062 2017 NYY CLE -40.3

Source: Retrosheet

Meanwhile, in the American League, some sanity has been restored with division series victories by the top-ranked Houston Astros and New York Yankees. Either way, it wasn’t exactly easy—the Astros required a double single-run victory (the latter tied a playoff record in 18 innings) to finish off the Seattle Mariners, while the Yankees had to tackle it 2-1. The series deficit against the Cleveland Guardians is to advance – but all season the best teams in the league will be playing for the AL pennant.

This puts an odd juxtaposition between the two championship streaks. Both are almost coin flips in our model – the Astros have a thin edge over the Yankees (54 to 46 percent) and the Padres are even weaker in the 52-48 favorites than the Phillies – but the combined quality of the two teams in each league It couldn’t be more different. The difference between the average Elo rating of championship contenders in AL (1578.7) and NL (1539.9) is 38.8 points. Going back to 1995, this is the biggest difference in the combined quality of LCS teams in a league at the end of any season:

Biggest disparities in LCS quality of the wild card era

Biggest gaps in average Elo rating between MLB teams in one league’s championship streak and that of another, 1995-2022

Year LG Teams Cover. elo LG Teams Cover. elo Openness
2022 GET HOU, NYY 1578.7 NL SDP, PHI 1539.9 +38.8
2021 NL ATL, LAD 1587.1 GET HOU, BOS 1549.5 37.6
2007 GET BOS, CLE 1569.3 NL ARI, COL 1537.3 32.0
2019 GET HOU, NYY 1589.0 NL STL, WSN 1559.5 29.4
2008 GET TBD, BOS 1566.5 NL PHI, LAD 1537.3 29.2
2009 GET NYY, ANA 1575.7 NL LAD, PHI 1547.5 28.2
2018 GET BOS, HOU 1599.3 NL MIL, LAD 1571.6 27.7
2014 GET BAL, KCR 1554.6 NL STL, SFG 1530.0 24.7
2003 GET NYY, BOS 1560.6 NL CHC, FLA 1536.2 24.3
2011 GET TEX, DET 1558.6 NL MIL, STL 1534.5 24.1

Source: Retrosheet

(Interestingly, only the edges last yearIt’s a run that includes the elite Braves and Dodgers teams in the NL but less heralded by the Boston Red Sox for pulling the AL average down.)

As a result, the ALCS winner should be heavily favored over the Fall Classic, as our model says the World Series winner has a 65 percent chance of making it out of the AL. But it all depends on which league’s end-of-season narrative – chaos in the NL or order in the AL – holds the upper hand at the end of the season.

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