The San Francisco Giants (a team that was expected to be the best in baseball) and the Boston Red Sox (a team few believed would be the top of baseball's most difficult divisions) are the two most surprising teams this season. Both teams failed to make the playoffs last season and both appeared to be in periods where they were undergoing relative retooling. However, the Red Sox (and Giants) are not low-budget, long-suffering franchises. Both have won multiple World Series over the past decade. They also rank amongst the top 10 in payroll for this year. These kinds of "hey-were good again" seasons are always possible in cities like Boston and San Francisco.The third-most impressive club, unlike its more famous peers, might not be the most well-known. It is one that almost never gets a postseason break and one that almost nobody would give even an outside chance to. Although the Seattle Mariners were considered one of the worst MLB teams, they now have a record above.500, and are tied with the New York Yankees in the AL wild card race as we approach the halfway point of the schedule. Seattle has the best winning record of all the 15 clubs currently in play.Seattle is MLB's most underrated winning team. Lowest preseason Elo ratings of 2021 MLB teams with winning records. Seattle Mariners 41 38.5191469 San Francisco Giants 47 27.649 1504 Chicago Cubs 43 36.5381506 Oakland Athletics 46 33.5881513 Cleveland Indians 41 33.5541513 Chicago White Sox 44 32.5771516 Milwaukee Brewers 45 32.5771518 Toronto Blue Jays 39 36.548 Houston Astros 48.61542 Houston Astros 47 37.519 1572 Los Angeles Dodgers.519 1572 Los Angeles Dodgers.519 1572 Los Angeles Dodgers.519 1572 Los Angeles Dodgers.603 1599 through games.603 1599 Source: Baseball-Reference.comThe 2021 Mariners had the 23rd-lowest Preseason Elo in any division (since 1969). This was despite them having a better than.500 record through the first 79 games. This is a team that has never been celebrated for putting together a winning half.The Mariners are a club that hasn't reached the postseason for two decades but still manages to be a surprise. In spite of modest preseason predictions, Seattle was close to the playoffs in 2016, 2016 and 2018. And even last season, the Mariners were closer to.500 than they thought. This years run is perhaps the most remarkable, simply because it has happened and, even more important, it hasn't.FiveThirtyEightYou might have thought that Kyle Lewis, last year's AL Rookie-of-the-Year, would lead the charge in center field. It is possible that you thought Marco Gonzales, the starter, would make it into the Cy Young discussion. Or that Kyle Seager, the veteran third baseman would have another great season in a career full of them. Perhaps Justus Sheffield, a lefty, would continue to fulfill the promise that made him one the best prospects in baseball with a solid 2020. Perhaps James Paxton, a once-great Mariner pitcher, would be able to rediscover his form pre-Yankees and create a great comeback story.None of these things have ever happened. Lewis was injured in his right knee last month, and was placed on the 60-day disabled list. Gonzales is 1-4 with a 5.10 ERA, and a worse fielding-independent pitching record. Seager is healthy, but on track for one of his worst seasons (1.87 runs above replacement per 162 matches). WAR has ranked Sheffield as one of the worst baseball pitchers. Paxton was only able to make one start before needing season-ending surgery.Related: What MLB Teams Should Make Midseason Deals? Continue reading. Continue reading.Instead, the 2021 Mariners have fuelled their first half with some outstanding performances from other places and lots of good luck along the way.Although J.P. Crawford's infielders and Ty France were both very good last year, they have made significant improvements for 2021. Crawford is a shining star, with a 5.56 WAR/ 162 ranking sixth among shortstops who have played at least two-thirds. He is also the only shortstop with an OPS that's at least 10 percent higher than average, and at least 10 runs fewer on defense. Seattle, France and Crawford are the only two teams that have at least three infielders this season.Crawford's glove and bat rank him among the top Most wins above replacement (WAR), per 162 MLB shortstops* player team(s). OPS+ Def. Runs Saved WAR/162 games Carlos Correa HOU 157 +6 843 Fernando Tats Jr. SD 201 -5 6.02 Isiah Kner-Falefa TEX 91 +1 5.88 J.P. Crawford SEA 111 +1 5.56 Xander Boerts BOS 155 -10 555 Trea Turner WSN 138 -3 5.03 Javier Bez 103 +4 4.30 Willy Adames MILT/TB 105 105 105 105 105 105 105 105 105 105 105 105 105 115 106 Through the games that took place between June 27 and July 1. Source: Baseball-Reference.comAfter struggling to a mere 80 ERA+ in his first two seasons after his move from Japan's Seibu Lions to the U.S., Yusei Kikichi has been a great starter. He now has a 121 ERA+ with 3.65 WAR per 162, and a 3.65 WAR/166. Kendall Graveman, the reliever, has been unhittable as he's taken away most of Rafael Montero's closing chances this season.It was refreshing to see a surprising cast of characters behind these Mariners' winning ways. (Seattle beat Chicago White Sox by two runs this weekend thanks to Taylor Trammell, an outfielder who had been hitting a buck fifty-eight before the action. The Mariners have had some luck, but they've also been able to reach their current position. They are 18-7 in one-run games, which means they are 23-31 all other contests. Seattle has exceeded its Pythagorean expectations more than any other team this season. Seattle is actually the team with the largest gap between their Pythagorean and actual winning percentages in the first 79 games. This difference has been there since 1969.The Mariners are now part of a lucky club. WPct Washington Nationals 2005.608 +.109 New York Mets 1984.570 Orioles 1978.438 +.106 San Francisco Giants 1977.409 +.096 San Diego Padres 1975.645 +.089 San Diego Angels 2008.649 Seattle Mariners 2001.734 +.089 San Diego Padres 1976.528 +.092.494 Seattle Mariners 2002.698.516.516.091 Seattle Mariners 2021.519.42277.526277.529Unfortunately, the winning percentages of the 19 other teams on the list fell from.571 to 79 games to an average of.491 during the rest of the season. The list's other entries can be instructive. While the 2001 Mariners won at a 113-win rate in the second half, the 2018 Mariners lost at a 98-win pace in its first-half. After their luck started to even out, the 2018 Mariners saw their winning percentages drop from.571 through 79 games to.491. The team lost eight games to the 97-win Oakland Athletics team in the playoffs. Seattle was thus eliminated from the postseason.Despite an impressive start to the season, this year's team has a longer chance of making the playoffs. Seattle's playoff chances would be only 22 percent if each remaining game was a coin flip. In reality, the playoff chances for Seattle are closer to 5 percent. The mere fact that the Mariners are in the conversation is more than anyone expected, especially considering the injuries theyve suffered. Seattle's run has been one the most pleasant surprises this season, regardless of whether it continues into the second half.Take a look at our MLB predictions.Which fictional coach is the most chaotic? FiveThirtyEightWhy is Patrick Mahomes so amazing? FiveThirtyEight
