We are just over a week into the MLB season and the Twins and Diamondbacks have the best records in their respective leagues. Few would expect either team to finish at the top of the standing by the end of the year. If neither team is really this good, how can we estimate their true talent? Simple, we can regress a team’s record to the mean.
Over a 162 games, teams tend to regress toward the mean. The average team in baseball has a .500 wining percentage. To regress a team’s record to the mean we need to add 67 games of .500 baseball (33.5 wins, 33.5 losses) to a team’s record. Here is a full explanation of why this works.
Minnesota is on pace to win 135 games while Arizona, if it maintained its current win rate, would top 120 wins. No team in baseball has ever won more than 116 games and no one expects that to happen this year either.
Regressing each team to the mean, the Twins true win pace is .527. This puts Minnesota on pace to finish the season 88-74. Arizona has an expected win rate the rest of the season of .527 as well (88-74 record).
Just as the Twins and Diamondbacks aren’t expected to keep winning at their current pace, the Blue Jays are just as unlikely to keep losing. Toronto, a playoff team from last season, has started the year 1-5. However, regressing the team to the mean gives the Jays a true pace record of 77-85 (instead of 27-135).
By getting an improved estimate of a team’s future winning percentage we can better understand the pace a squad is on. Of course not all clubs have an underlying talent of a .500 team (Cubs for example come to mind). Next week we will regress each team using preseason expectations from FanGraphs.
2017 MLB Season
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Regressed MLB Records
|Team||Record||Win%||Regressed Win%||True Pace Record|
|Los Angeles Angels||5-2||0.714||.52||87-75|
|Tampa Bay Rays||5-3||0.625||.513||86-76|
|New York Mets||4-3||0.571||.507||84-78|
|Boston Red Sox||3-3||0.5||.5||83-79|
|Los Angeles Dodgers||4-4||0.5||.5||83-79|
|San Diego Padres||4-4||0.5||.5||83-79|
|New York Yankees||3-4||0.429||.493||81-81|
|Chicago White Sox||2-3||0.4||.493||81-81|
|San Francisco Giants||3-5||0.375||.487||80-82|
|Kansas City Royals||2-5||0.286||.48||79-83|
|St. Louis Cardinals||2-5||0.286||.48||79-83|
|Toronto Blue Jays||1-5||0.167||.472||77-85|