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Major League Baseball Is About To Get Random

Baseball’s playoffs are upon us once again, and as is the case every year, we don’t know much about what will happen. The postseason has a tendency to make fools of us all: Wild cards have won before, they will win again, and even the best team in the league doesn’t have much better than one-in-four odds of winning the World Series. But that doesn’t mean we can’t use all the sabermetric tools at our disposal — including FiveThirtyEight’s MLB Elo ratings — to make an informed guess.

Roughly speaking, you can divide this year’s playoff teams into three tiers: On the top, you have three powerful division-winning teams in the Cubs, Dodgers and Red Sox, who together take up 60 percent of the available World Series probability (according to Elo). The next tier consists of the remaining division winners, all of whom are superlative in some respects but also have fairly significant flaws. And finally, you have the wild-card winners — some of which are more dangerous than others, but all of which have to fight through the dreaded play-in game.

If you had to pick an eventual champion, you’d choose from the top tier of teams — though even in a year of decreased parity, they’re far from sure things. To sort out the teams within each tier, here’s a deeper look at every club in the playoff field.

Tier A — The Powerhouses

Chicago Cubs (26 percent odds of winning the World Series)

The Chicago Cubs won 103 games, the most of any team since 2009 and eight more than any other team this season. But their season has very much been a tale of two halves. Through July 1 the Cubs had racked up a +161 run differential, a number on track to challenge the mark set by the 1939 Yankees as greatest of all time. Since then, in about the same number of games, they’ve only put together a run differential of +91, or a bit more than half as good as they were before.

So which version of the Cubs will show up for the playoffs? It might not actually matter. Although having a more dominant team is always better, the randomness of the playoffs means that a great team can always lose. Either version of the Cubs — the record-breakers or the merely ordinary division-winning outfit — would likely be World Series favorites, but neither would have even 50-50 odds of winning it all. Our projections contain a little bit of both versions, and they easily give Chicago the best chance of any team to make, and win, the championship round, at 43 percent and 26 percent, respectively.

Boston Red Sox (19 percent)

The Chicago Cubs may have captured the lion’s share of the headlines this year, but the Boston Red Sox have been surprisingly dominant. They have the second-best Elo rating of any MLB team heading into the playoffs, 14 points behind the Cubs and 24 points ahead of their nearest competition (the Toronto Blue Jays).

Although Boston won only 93 games, fifth-most in baseball, it also faced more difficult opposition in the American League East, which (as usual) featured three playoff-worthy teams. So the Red Sox are probably scarier than their record would indicate — particularly on offense, where they scored an MLB-best 5.42 runs per game during the regular season (topping even the Coors Field-inflated Colorado Rockies). Their major weakness — and the biggest factor separating them from the Cubs’ lofty perch — is mediocre pitching. But the format of the playoffs will allow them to hide their back-end starting pitchers and hand more innings to David Price and Rick Porcello, so expect the Red Sox to pitch a little better in the postseason than they did in the regular season.

Los Angeles Dodgers (15 percent)

The Dodgers have had the most eventful season of any division champion. Between injuries, broken perfect games, and the near trade and demotion of erstwhile star Yasiel Puig, Los Angeles has had more drama than you’d expect from a 91-win division champion. The injuries have taken a particular toll on the starting pitchers: No single starter for the Dodgers pitched as many as 200 innings during the regular season.

With all of those injuries, you might expect the Dodgers to enter the postseason as a depleted husk of their former selves. And yet they are on track to start Clayton Kershaw, Rich Hill and Kenta Maeda, a top three that would be the envy of many other contenders. That talented starting rotation helps give the Dodgers the third-best shot at the title — assuming they can stay healthy through the postseason, that is.

Tier B — The Good-But-Not-Great Division Winners

Cleveland Indians (8 percent)

The Indians claimed the relatively weak American League Central, with the Detroit Tigers serving as their only real competition. (Detroit eventually finished 8 games back.) Cleveland did amass 94 wins and posted the fourth-best run differential in baseball, although they also benefited somewhat from good sequencing (as measured by FanGraphs’ BaseRuns) and unexpectedly great performances from guys like Tyler Naquin and Jose Ramirez.

Maybe the Indians’ biggest secret weapon is their bullpen. The team’s deadline trade for Andrew Miller gave it a bona fide relief ace; Miller has allowed only five runs to score in 29 innings pitched since coming to Cleveland. Plus, manager Terry Francona has been surprisingly flexible about using Miller in the most important situations, regardless of inning. If Francona can continue his innovative managing into the postseason, the Indians will have a slight but significant edge that the statistical projections don’t fully take into account.

Washington Nationals (8 percent)

The Nationals are sneaky good. Our Elo-based projections give them only a 16 percent chance of making the World Series, but they had baseball’s third-best run differential during the regular season. The Nats are well-rounded: They ranked among the 10 best in both runs scored and runs allowed per game, boasting a Cy Young candidate in Max Scherzer as well as the sixth-best bullpen in the league, as measured by wins above replacement.

So why aren’t their chances better? Part of it is the quality of their competition, both in the past and in the future. They amassed such strong numbers partially by beating up on their NL East rival Braves and Phillies, two of the worst teams in the league according to run differential.1 What’s more, their path to the World Series starts with the Dodgers and may also go through the Cubs, two of the league’s top-tier teams. Making matters worse, they lost All-Star catcher Wilson Ramos to injury, and they won’t have Stephen Strasburg in the Division Series either. Add it all up, and Washington has a tough — if not insurmountable — road to the Series.

Texas Rangers (8 percent)

The most exceptional thing about the Texas Rangers so far this year has been their incredible record in one-run games. They have piled up a 36-11 mark in such contests, helping them win 95 games despite an overall run differential of only +8 on the season. In fact, that mark is the worst among all playoff teams, suggesting that the Rangers have spent the season playing above their heads.

It’s easy to assume that because sabermetricians can’t explain one-run performance, it must be random. That would be a mistake: Such performances shouldn’t be completely discarded. But even if you believe that the Rangers have gotten special, sustainable contributions from their bullpen or manager, their .766 winning percentage in one-run games must be at least partially thanks to good fortune — and as a result, they may not be as good as their record suggests. Texas’s best-in-the-AL record gives it an inside track to the World Series, but since the Rangers also sport the worst Elo rating of any team in the entire playoff field, they have a mere 8 percent probability of winning it all, no better than the other second-tier division champions.

Tier C — The Wild Cards

Toronto Blue Jays (6 percent)

Of all the wild-card clubs, Toronto has the highest probability of making (and winning) the Series. In fact, their Elo rating is higher than that of several division winners, which suggests that the Jays are a very good team. Toronto’s only fault is that they share a division with the superior Boston Red Sox, confining them to a do-or-die game that could end their postseason before it really begins. Even the most imbalanced matchup in MLB is usually a 60-40 proposition, so the Jays can’t count on a win against the Orioles.

If they do win that wild-card game, however, the Blue Jays will see their postseason odds soar. Their starting pitching has been excellent, and their offense is great (as usual). Provided it can overcome Baltimore, Toronto could end up making a surprise run deep into the postseason. The one glaring issue is its bullpen, which ranks second-worst among playoff entrants in ERA. If the starters end up exiting games early, it will expose a relief crew with few reliable arms.

Baltimore Orioles (4 percent)

The Orioles’ Elo rates them as the second-weakest team of the playoffs, ahead of only the Rangers. However, unlike the Rangers, the Orioles must win a game against the Blue Jays to advance to the ALDS. Elo only gives Baltimore a 44 percent chance in that game against the Jays, and a depressingly low 4 percent probability of eventually winning the championship.

The Orioles’ bullpen is good — it has the third-best ERA among the playoff contenders — and especially top-heavy, featuring a rare Cy Young-contending reliever in Zach Britton. But that won’t be enough to get them to the World Series unless their mediocre rotation pitches better. The Orioles didn’t have a single starter post more than three wins above replacement during the regular season, while most of their fellow playoff teams had two or three starters who were at least that good. Savvy bullpen management can only go so far; barring some very good luck, expect the Orioles to make an early exit.

New York Mets (3 percent)

The Mets are hard to figure out. On the one hand, they limped into the playoffs on the back of two surprisingly productive rookies (Seth Lugo and Robert Gsellman) after their rotation collapsed because of injuries. Add to this toll the lingering problems with their starting lineup and it’s hard to believe the Mets could realistically overcome the strong top tier of National League teams to capture a second consecutive pennant.

On the other hand, the Mets may have the best bullpen out of all the playoff teams, according to WAR. We know that relievers get a greater share of a team’s innings pitched in the postseason, so the superlative bullpen may make up for their rookie starters. If, that is, manager Terry Collins allows them to: He has a habit of leaving his starters in too long, which can be fatal in the postseason.

San Francisco Giants (3 percent)

While the Cubs fell in the second half from historically great to merely fantastic, the Giants dropped from probable division winners to meltdownprone also-rans. Their collapse hasn’t quite been historic, but their second-half statistics don’t bode well for the playoffs (at least, to the very limited extent that second-half performance matters). More worrisome, their bullpen has been atrocious, stretching even Bruce Bochy’s ability to manage around it.

Then again, the Giants have a tradition of overcoming regular-season problems to overperform in October, and they still have Madison Bumgarner. Still, when a team’s playoff hopes rest on numerology (it’s an even year!) and repeating one of the greatest postseason performances of all time, it’s reasonable to conclude that they simply aren’t very likely to win the World Series. Elo agrees with that assessment, giving them only a 3 percent shot, even-year magic be damned.

FiveThirtyEight: The ALDS matchup between Toronto and Texas could get ugly


  1. No other division has more than one of the five worst teams in the league, and Washington outscored the two in its division by a combined 66 runs during the regular season.

Rob Arthur is a former baseball columnist for FiveThirtyEight. He also wrote about crime.