We Crunched The Numbers On 2021’s Best (And Worst) Teams

As we look back on the highs and lows of 2021’s sports calendar, it’s tempting to crown certain teams as the best — or worst — in all of sports, not just their sport. That’s been difficult to do across the pro sports landscape … until now.

We here at FiveThirtyEight made a concerted effort to expand the number of leagues for which we keep Elo ratings and predictions. We added an interactive to track WNBA odds in May and rolled out an NHL forecast model just in time for hockey season in October. That gave us ratings and interactives for five major North American pro sports leagues — the NFL, NBA, MLB, NHL and WNBA — which we can also use to look back on the most dominant (and disappointing) performances of the year as a whole.

When measuring a team’s Elo performance in the past, we have tended to blend together three different measures: a team’s peak Elo when it was at its absolute best; its average Elo across the entire season (including playoffs); and its final Elo by season’s end. We can extend that concept by calculating those metrics for each franchise in each league across the 2021 calendar year, regardless of whether that included a single season (i.e., MLB) or stretched across multiple seasons (i.e., the NBA).¹ And since the range of Elo ratings differs across leagues, we took one final step — calculating the z-score (which measures the number of standard deviations above/below average) for each blended Elo relative to its sport’s competition. With all of that in mind, here were the best and worst of our Big Five leagues in 2021:

(All 2021 ratings are as of Dec. 15.)

Best champion: Tampa Bay Lightning, NHL (+1.73 z-score)

The Bolts came into 2021 as the defending Stanley Cup champions, so they were starting out in better shape than most teams. But the Lightning’s 2020 championship had come under unusual circumstances (no fans!) in the league’s COVID-19 bubble, and they began their repeat bid missing some key pieces (such as the injured Nikita Kucherov), while it looked like they would also have tougher competition atop the league. Nonetheless, Tampa powered through. After finessing their salary-cap situation to finish tied for the league’s eighth-best record during the regular season, they went 16-7 in a postseason that saw Kucherov’s controversial return and featured all of the other favorites getting picked off before the final. A five-game championship triumph against the overmatched Montreal Canadiens capped off just the second back-to-back Cup run since 1998, cementing Tampa Bay as arguably the greatest team of the NHL’s salary-cap era … and Elo’s best champ of 2021.

Best team that didn’t win it all: Los Angeles Dodgers, MLB (+2.31 z-score)

Like the Lightning, the Dodgers entered 2021 as defending champs from an abbreviated 2020 campaign that staged its postseason at neutral sites. And on paper, the Dodgers might have been even more talent-laden this year than they were the year before. But in reality, the season was far from a smooth ride, even though L.A. pulled off some impressive in-season acquisitions and ended up winning 106 games (second-best in MLB behind the archrival San Francisco Giants). In the postseason, the Dodgers survived the wild-card game and even defeated the Giants in a contentious division series matchup, but they fell short in an NLCS rematch with the eventual champion Atlanta Braves. Along the way, Los Angeles made decisions that cost them both money and trust, and reignited questions about whether the team has won as much as it should have given its talent. But at the same time, they were baseball’s most dominant team across the majority of the season — and the top “paper champion” of major pro sports this year.²

Worst team: Jacksonville Jaguars, NFL (-2.22 z-score)

As impressive as the top teams of 2021 were, there was no shortage of candidates for worst team from the opposite end of the talent spectrum. Some teams were tanking; some were cursed; some were named the Jets. Several hailed from a single city — we’re sorry, Detroit —  that we anointed the current Capital of Bad Sports. But in the end, no franchise could compare to the mess that played out in Jacksonville this year. And most of it came down to one man: Urban Meyer. Meyer’s tenure at the Jaguars’ helm was an unmitigated disaster — both on and off the field — after he was lured out of college football retirement to coach in the pros. He was unable to harness the rookie potential of No. 1 overall draft pick Trevor Lawrence at QB, unable to coax anything out of his offense or defense, and seemingly unable to go as much as a week without an embarrassing scandal. Fired just 13 games into the 2021 season, Meyer was the worst coach of the year, and he dragged his team down with him.

Most improved team: Golden State Warriors, NBA (z-score +2.30 from 2020)

In a battle with their Bay Area MLB counterparts and a host of NBA peers, the Golden State Warriors easily produced the best turnaround story of 2021. It started last season, when the team emerged from a Steph Curry-less nightmare to finish above .500 and nearly return to the playoffs. But the real magic was only beginning to return. This season, the Warriors have found another gear entirely, arguably playing like the league’s most impressive team in the early going. As ESPN’s Kevin Arnovitz recently wrote, the current Warriors are eerily reminiscent of the pre-Kevin Durant version that set an NBA record for wins in a single season. That’s a scary proposition for the rest of the NBA — and a fitting level of form for Golden State to end its wildly improved 2021 calendar year on.

Least improved team: Oklahoma City Thunder, NBA (z-score -2.12 from 2020)

The Thunder were one of the NBA’s surprising success stories of 2020, finishing fifth in the Western Conference and taking the Houston Rockets to seven games in the first round of the playoffs in the bubble. But after an incredibly busy offseason heading into 2021, OKC’s remade roster fared worse this year. A lot worse. Under new coach Mark Daigneault, the team dipped to 14th out of 15 teams in the West last season, and it’s tied for fewest wins in the West this season — one which saw the Thunder lose by a staggering NBA-record margin of 73 points against the Memphis Grizzlies in early December. Much of this is part of OKC’s long-term rebuilding plan, but even if it’s largely by design, no team in our data set saw its fortunes fall further from 2020 to 2021 than the Thunder did.