Skip to main content
ABC News
The MLB Contender Nobody Saw Coming

Relative to preseason expectations, the two most impressive teams in baseball so far this season have probably been the San Francisco Giants and Boston Red Sox — a pair of clubs few thought would be headlining baseball’s two toughest divisions. But while both teams missed the playoffs last year and appeared to be in periods of relative retooling, the Red Sox and Giants are not exactly long-suffering, low-budget franchises. (Both have won multiple World Series in the past decade; both also rank among the top 10 in payroll this year.) This kind of hey-we’re-good-again season is always at least possible in places like Boston and San Francisco.

Unlike those more prestigious peers, the third-most-impressive club might be one that nobody gave even an outside chance — and one that almost never catches a postseason break. Though the Seattle Mariners started the year looking like one of MLB’s worst teams on paper,1 here they are, above .500 and tied in the AL wild-card race with the New York Yankees (of all teams) as we near the halfway point in the schedule. Out of the 15 clubs with winning records right now, Seattle is easily the one that overcame the humblest of opening day expectations:

Seattle is MLB’s most underestimated winning team

Lowest preseason Elo ratings for 2021 MLB teams with winning records

Team Wins Losses WPct Preseason Elo Rating
Seattle Mariners 41 38 .519 1469
San Francisco Giants 50 27 .649 1481
Boston Red Sox 47 31 .603 1504
Chicago Cubs 42 36 .538 1506
Oakland Athletics 47 33 .588 1513
Cleveland Indians 41 33 .554 1513
Chicago White Sox 45 32 .584 1516
Milwaukee Brewers 45 33 .577 1518
Toronto Blue Jays 40 36 .526 1519
Tampa Bay Rays 47 32 .595 1533
New York Mets 40 33 .548 1540
Houston Astros 48 30 .615 1552
San Diego Padres 47 33 .588 1561
New York Yankees 40 37 .519 1572
Los Angeles Dodgers 47 31 .603 1599

Through games of June 27.


If we expand that list to look at the entire divisional era (since 1969), the 2021 Mariners also had the 23rd-lowest preseason Elo of any team that was better than .500 through the first 79 games of a season.2 Simply put, this is one of the most unheralded teams to put together a winning first half in modern memory.

For a club that hasn’t made the postseason in two decades, the Mariners do have the capacity to surprise every now and again. Seattle flirted with the playoffs in 2014, 2016 and 2018 despite modest preseason predictions, and even last season the Mariners hung around closer to .500 than we thought they would. But this year’s run might be the most surprising, simply because of how it has — and, more importantly, hasn’t — happened.

Every baseball fan should know these Negro League stars | FiveThirtyEight

If you were told Seattle would be winning more often than not in the season’s first half, you might have expected center fielder Kyle Lewis — last year’s AL Rookie of the Year — to star front-and-center. You might have thought starter Marco Gonzales would figure into the Cy Young conversation, or that veteran third baseman Kyle Seager would produce another gem of a season in what has been an underrated career full of them. Or perhaps lefty Justus Sheffield would build on a solid 2020 to deliver on the promise that once made him one of the 30 best prospects in baseball. Maybe once-great Mariner starter James Paxton would even rediscover his pre-Yankees form and build a great comeback story.

But none of those things have happened. Lewis hurt his right knee late last month and was recently placed on the 60-day injured list. Gonzales is 1-4 with a 5.10 ERA and an even worse fielding-independent pitching mark. Seager is healthy but on pace for one of the worst seasons (1.87 wins above replacement per 162 games) of his career. Sheffield has been one of the worst pitchers in baseball by WAR. And Paxton lasted exactly one start before requiring season-ending surgery.

A player in midpitch with his arm above his head.

related: Which MLB Teams Should Be Making Midseason Deals? Read more. »

Instead, the 2021 Mariners have fueled their first half with a bunch of breakout performances from other places — and a lot of good fortune along the way. 

Infielders J.P. Crawford and Ty France were already pretty good last year, but both have improved significantly in 2021. Crawford in particular is playing like a star — his 5.56 WAR per 162 ranks sixth among players who’ve logged at least two-thirds of their games at shortstop. (He’s also the only qualified shortstop this season with an OPS at least 10 percent better than average and at least 10 runs saved on defense.) Between Crawford and France, Seattle is one of only 12 teams with two or more infielders on pace for at least 3.0 WAR this season.

Crawford’s bat and glove rank him among the best

Most wins above replacement (WAR) per 162 team games for 2021 MLB shortstops*

Player Team(s) OPS+ Def. Runs Saved WAR/162 Games
Carlos Correa HOU 157 +6 8.43
Fernando Tatís Jr. SD 201 -5 8.38
Brandon Crawford SF 137 +3 6.02
Isiah Kiner-Falefa TEX 91 +9 5.96
Bo Bichette TOR 120 +1 5.88
J.P. Crawford SEA 111 +10 5.56
Xander Bogaerts BOS 155 -10 5.55
Trea Turner WSN 138 -3 5.03
Javier Báez CHC 103 +4 4.30
Willy Adames MIL/TB 105 +3 3.91

*To qualify, a player must have played at least two-thirds of his games as a batter at shortstop.

Through games of June 27.


On the mound, starter Yusei Kikuchi has been excellent — with a 121 ERA+ and 3.65 WAR per 162 — after struggling to a mere 80 ERA+ over his first two seasons following his posting to the U.S. from Japan’s Seibu Lions. And reliever Kendall Graveman has been unhittable (opposing batters have a .450 OPS) as he’s wrested away most of the team’s closing opportunities from Rafael Montero this season.

It’s been refreshing to see something of an unheralded cast of characters power these Mariners’ winning ways. (Even this weekend, outfielder Taylor Trammell — who was hitting a buck-fifty-eight going into the action — helped Seattle upset the Chicago White Sox with a two-homer game.) But of course, the Mariners have also benefited from quite a bit of luck to get to where they are. They’re 18-7 in one-run games — meaning they’re 23-31 in all other contests — and no team has exceeded its Pythagorean expectation more than Seattle so far this season. In fact, Seattle has the 20th-largest gap between its actual and Pythagorean winning percentages through the first 79 games of a season by any team since 1969:

The Mariners have joined a lucky club this season

Biggest positive gaps between actual and Pythagorean winning percentages through the first 79 games of a season (with winning percentages over the remainder of the regular season), 1969-2021

WPct through 79 Gms
Team Season Actual Pythag Luck Rem. WPct
Washington Nationals 2005 .608 .499 +.109 .398
New York Mets 1984 .570 .461 +.109 .542
Baltimore Orioles 1978 .544 .438 +.106 .573
Cincinnati Reds 1970 .709 .609 +.100 .554
Detroit Tigers 1974 .532 .434 +.098 .361
St. Louis Cardinals 1994 .513 .416 +.096 .361
San Francisco Giants 1997 .570 .475 +.094 .542
New York Mets 1972 .582 .490 +.092 .481
Seattle Mariners 2018 .608 .516 +.091 .494
Seattle Mariners 2001 .734 .645 +.089 .699
San Diego Padres 1974 .430 .345 +.086 .313
Los Angeles Angels 2008 .608 .525 +.083 .627
Cincinnati Reds 2004 .532 .449 +.082 .410
Pittsburgh Pirates 2010 .354 .273 +.081 .349
Houston Astros 1979 .608 .527 +.081 .494
New York Yankees 2004 .633 .553 +.080 .614
Chicago Cubs 1977 .633 .554 +.079 .373
Minnesota Twins 2017 .506 .429 +.077 .542
Oakland Athletics 1992 .582 .505 +.077 .602
Seattle Mariners 2021 .519 .443 +.076


The bad news is that, on average, the other 19 teams on the list saw their winning percentages drop from .571 through 79 games to .491 over the remainder of the season. And Seattle’s other entries on the list can be instructive in that regard: While the mighty 2001 Mariners kept chugging along, winning at a 113-win pace in the second half of the season, the 2018 version dipped from a 98-win first-half pace to an 80-win second-half pace after its luck began to even out. That team ended up missing the playoffs by eight games to a 97-win Oakland Athletics team, so the inability to maintain its first-half pace cost Seattle a postseason berth. 

This year’s team faces even longer odds to make the playoffs, despite the impressive start to the season. Even if every remaining game were a coin-flip, Seattle would have only a 22 percent playoff probability. (In reality, its playoff chances are more like 5 percent.) But the mere fact of being in the conversation is more than anybody expected from the Mariners going into 2021, particularly given the injuries they’ve faced. Whether it lasts into the second half of the schedule or not, Seattle’s run has been one of the most pleasant surprises of the season so far.

Check out our latest MLB predictions.

Who’s the most chaotic fictional football coach? | FiveThirtyEight

What makes Patrick Mahomes so great? | FiveThirtyEight


  1. They ranked 24th in our preseason Elo rankings.

  2. Obviously this excludes 2020, since it only had 60 games in its entirety.

Neil Paine was the acting sports editor at FiveThirtyEight.