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The Boom-Or-Bust Red Sox Are At It Again

The Boston Red Sox were one of baseball’s great disappointments the past two seasons, going a combined 108-114 in 2019 and 2020 after they won the World Series with a 108-54 record in 2018. While everything went right for Boston in that championship run, a combination of regression and injuries to highly paid stars dragged the Sox down the next season; the descent was further accelerated when the team traded former MVP Mookie Betts to the Dodgers in February 2020. Going into 2021, Boston was supposed to improve slightly, with a preseason projected record of around .500, under the assumption that some of the team’s 2020 underperformers would bounce back and its offseason pickups would deliver better results. But few would have expected the Red Sox to play quite as well as they have out of the gate this season: a 10-6 record, good for first place in the AL East by several games, with a top-five offense and one of the most improved pitching performances in the game so far.

This kind of rapid turnaround is nothing new for the franchise, though. In 2012, the Red Sox followed a 90-win, near-playoff campaign with a 69-93 disaster in manager Bobby Valentine’s lone season at the helm in Boston. All they did the next year was bounce back to 97-65 and win the World Series … then fall below .500 in each of the two seasons after that. Then, after making progress with a couple of playoff appearances in 2016 and 2017, they put up one of the most dominant single seasons in MLB history en route to the 2018 title … before collapsing yet again. And now their history of bouncing back quickly from catastrophe might be repeating itself as well.

Truly, Boston fans have seen their team ride one of the weirdest roller-coasters in baseball history. If we add up their absolute season-over-season changes in winning percentage since 2011 — plugging in our forecast model for 2021’s numbers — the Red Sox are currently in the second-most volatile 10-year stretch of season-to-season changes of any team since World War II, trailing only the Seattle Mariners from 2000 through 2010.

Red Sox fans have been on a roller-coaster ride

MLB teams with the largest aggregate season-to-season winning percentage swings over a 10-year span, 1946-2021

Winning Percentages
Team Range of Years Best Worst Tot. 10-yr WPct Movement
Mariners 2000-2010 .716 .377 1.097
Red Sox 2011-2021* .667 .400 1.072
Diamondbacks 1998-2008 .617 .315 0.981
Cubs 1997-2007 .552 .401 0.949
Athletics 1946-1956 .545 .318 0.940
Dodgers 1983-1993 .586 .389 0.932
Indians 1985-1995 .694 .352 0.914
Angels 1994-2004 .611 .409 0.909
Tigers 1988-1998 .543 .327 0.898
Giants 1946-1956 .630 .396 0.877
Athletics 1973-1983 .605 .333 0.873
Cardinals 1978-1988 .623 .426 0.869
Indians 2003-2013 .593 .401 0.866
Twins 2009-2019 .623 .364 0.855
Padres 1989-1999 .605 .377 0.846

*The 2021 number is Boston’s forecasted winning percentage from the FiveThirtyEight prediction model, through games of April 18.

Source: fangraphs

Boston’s upheaval also extended from the field into the locker room and the front office. Over the span of a decade, the Red Sox have gone through four different baseball operations decision-makers1 and made five managerial changes — including the ouster and subsequent rehiring of current manager Alex Cora, who left the team in January 2020 over his role in the Houston Astros’ sign-stealing scandal but returned in November.

As we’ve seen across many sports, chaos in management often leads to chaos on the field. So in that sense, the dips in Boston’s roller-coaster trajectory are not surprising. What is surprising, however, is that the team has managed to ride out those low points and rise again so frequently.

Deep pockets certainly help with that. The Red Sox rank seventh in payroll this season and were baseball’s biggest spenders as recently as 2019. But Boston also spent much of the 2010s loading up with a formidable farm system, even as it was experiencing its dizzying highs and lows at the MLB level. The ability to contend in the moment while also building for the future has become a hallmark of the most successful franchises in the game, and many of Boston’s best players from 2018 (Betts, Andrew Benintendi, Xander Bogaerts, Jackie Bradley Jr., Eduardo Rodríguez, Rafael Devers, etc.) were drafted by the Red Sox or otherwise grew in their farm system while the big club was alternating championships with subpar seasons.

Of course, as is his tendency, former president of baseball operations Dave Dombrowski gutted the team’s stockpile of prospects in service of short-term success, which both worked brilliantly — flags fly forever! — and looked less-than-great during the post-championship collapse. But Chaim Bloom, Dombrowski’s front-office successor, has been working to improve Boston’s future talent recently, building up from dead last in Baseball America’s 2019 organizational rankings to No. 21 this spring. Having both a lot of money to spend and a consistent pipeline of prospects remains the best formula for teams hoping to turn around their fortunes, and that’s a big reason the Red Sox are always in a good position to pivot from losing to winning in a hurry.

It also helps to have veterans with the track record and upside to improve on their down seasons. Designated hitter J.D. Martinez, an MVP candidate in 2018, was the ninth-worst player in baseball by wins above replacementour JEFFBAGWELL metric to blend WAR from and FanGraphs, for which you can download data on GitHub.

">2 last year, but he’s bounced back to be MLB’s 21st-best by WAR so far this year, with a scorching 1.190 OPS. A similar story could be told for Devers, whose WAR per 162 team games dipped from 5.7 in 2019 to 1.7 in 2020; he’s rebounded to play at a 3.9-WAR pace (i.e., a borderline All-Star performance) in 2021. Pitchers Nathan Eovaldi and Matt Barnes have been among the most effective in the league this year, and infielder Christian Arroyo has been instrumental in boosting Boston’s WAR ranking at second base from a dismal 29th in 2020 to eighth this season.

Add in the ongoing excellence of Bogaerts at shortstop and the strong play of outfielder Alex Verdugo, who was acquired from Los Angeles in the Betts trade, and Boston has done plenty to exceed expectations already in the first month of 2021. Although our model remains somewhat skeptical that the Sox can keep winning at quite the same pace throughout the season — we still give them just a 35 percent chance to make the playoffs — it’s not as though their division rivals have staked a strong counterclaim to Boston’s hot start. (The Red Sox are the only AL East team with a record above .500, while the archrival Yankees are currently in last place at 5-10.) If Martinez and company continue to bounce back, and if erstwhile ace Chris Sale returns from Tommy John surgery for the second half of the schedule looking anything like his old self, don’t be surprised if Boston’s strange history of rising from the ashes of horrible seasons gets a brand-new chapter this year.

Check out our latest MLB predictions.


  1. Including general managers (Theo Epstein and Ben Cherington), a president of baseball operations (Dave Dombrowski) and current chief baseball officer Chaim Bloom.

  2. Using our JEFFBAGWELL metric to blend WAR from and FanGraphs, for which you can download data on GitHub.

Neil Paine was the acting sports editor at FiveThirtyEight.