The Best MLB Teams Of All-Time, According To Elo

One hundred and 10 years ago, the Chicago Cubs ended the regular season with a 116-36 record. That .763 winning percentage is the best in modern baseball history by a comfortable margin, but the Cubs went on to drop the World Series to the White Sox in six games. Might they still be the greatest team in baseball history?

We recently calculated historical Elo ratings for every team after every game as part of our Complete History Of MLB interactive graphic. (We’ve done the same for the NBA and NFL.) Elo ratings are one of our preferred metrics at FiveThirtyEight, because their simple inputs make them useful for comparing the relative strengths of teams across the entire history of a league. We can also use Elo to calculate season ratings for every MLB team since 1903, when the first modern World Series was played.² We arrived at an overall season rating — what the table below calls “composite” Elo — by blending each team’s peak, average and final Elo for each season. This lets us take into account a team’s highest level of performance, its sustained performance throughout the season and, broadly, how well it did in the postseason.³

So who comes out on top? The 1906 Cubs have the highest peak Elo, but because of their World Series loss, they rate as the second-best team since 1903, behind the 1939 New York Yankees. We ranked all 2,374 team-seasons from 1903 to 2015 — you can explore them below:

Our Elo ratings find that the league was a bit more top-heavy in its earlier decades. If you scan through the top of the list, you’ll notice that most of the best seasons since 1903 happened more than 50 years ago — in fact, 71 of the 100 best seasons fall before 1960. The New York Yankees’ insane dominance in the 1920s, ’30s, ’40s and ’50s is responsible for a lot of this imbalance. Twenty-five of the 100 best seasons are Yankees seasons from those decades:

After the Yankees dynasty declined, MLB’s best teams started to be a lot less good. The 1960s were understandably weak — with just two teams in the Elo top 100 — because MLB expanded by eight teams during this span. The 1980s don’t have the same excuse, and the decade’s best squad — the 1986 Mets — rates as only the 62nd-best team ever. The first six seasons of the 2010s were similarly middling; of the teams from those years, the 2011 Phillies rank the highest on the all-time list, at No. 76.

Although that Philadelphia team lost in the division series, it still rates as the best Phillies squad in history. Here’s every franchise’s best team ever:

The 1939 Yankees and 1906 Cubs are in a league of their own, more than 10 Elo points ahead of the other franchises. The Marlins have only been around since 1993, but it’s still sort of sad that their best team ever (World Series champions no less!) is just the 601st-best team ever. The Colorado Rockies, a franchise that was also born in 1993, are about as sad, but without the World Series rings. The San Diego Padres have had a much longer commitment to mediocrity; the franchise’s best team in its 47 seasons of existence comes in at No. 480. Fans of the Braves, Dodgers, Red Sox, Tigers, White Sox, Twins and Phillies may also be disappointed by their team’s position in this list. All seven franchises go back to 1903, but none of their teams in the last 113 seasons have come close to cracking the top 25.

But great seasons aren’t the only way to be an exceptional baseball team. Here’s every MLB franchise’s worst squad ever:

The 2003 Detroit Tigers lost 119 games, winning five of their last six to avoid the 120-loss modern record set by the 1962 Mets in their first season as a franchise. Elo isn’t fooled, though — the 2003 Tigers had a slightly worse run differential than the 1962 Mets and have a slightly lower rating here. The 1904 Washington Senators, now the Twins, were even more terrible according to Elo, going 38-113 (the equivalent of a 121-loss modern 162-game season). Angels fans probably don’t look back on the 91-loss 1969 season too fondly, but, compared with the other franchises’ lousiest seasons ever, it’s not a bad low point, ranking just 279th-worst.

So what will come in 2016? The Atlanta Braves and Cincinnati Reds have had a rough start and could make a run at new Elo lows for their franchises. But the real team to watch is the Chicago Cubs, who have started the season at 24-6 with an incredible +102 run differential. It’s a hard pace to keep up, but if they do, the Cubs could make a run at becoming one of the greatest teams of all time.

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