Most years, the American League’s Most Valuable Player award is basically Mike Trout’s hardware to lose. In his five full MLB seasons, the Los Angeles Angels outfielder never finished lower than second in MVP voting — winning the honor twice — and he led the AL in wins above replacement each of those campaigns.

Before he got hurt in early August, Trout was well on his way to extending that streak this season, positioning himself for another strong run at the MVP (or at least another hearty Trout-for-MVP debate). But Trout’s injury sidelined him for nearly a month, and he wasn’t quite himself after coming back; moreover, his Angels are going nowhere in the standings. Meanwhile, his rivals have been on fire, making their dueling MVP cases — while playing together in the same lineup.

Yes, Mookie Betts and J.D. Martinez of the Boston Red Sox are arguably the two front-runners now for the AL MVP. And the choice between teammates could prove to be yet another battleground in the divide between old- and new-school ways of judging player value. By the advanced metrics, Betts is having a historic season; Martinez, though, could pull off an impressive statistical feat that hasn’t been accomplished since the 1950s.

It makes sense that a pair of MVP candidates would emerge from a season as charmed as the one unfolding in Boston this summer. At 98-46, the Red Sox have the best record in baseball and are tracking to finish the year with 109 wins, which would be the most in MLB since the Seattle Mariners won 116 in 2001. Such a powerhouse team doesn’t happen without multiple great performances, and Betts and Martinez have supplied plenty of greatness this year. (To go with the great pitching season of Chris Sale, who might win the Cy Young despite missing most of August and early September with an injury.)

For his part, Betts has been squarely in the MVP discussion all season long. Though he trailed Trout in WAR early — as Trout seemed to be launching maybe the best individual season in MLB history — Betts also kept surprisingly close to his fellow outfield star with a historic start of his own. After Trout was injured, Betts passed him in WAR and hasn’t really looked back, pouring on a .942 on-base plus slugging (seventh-best in the AL) since the All-Star break with strong defense in right field.

In terms of WAR, Betts is on pace for 10.4 on the season, which would place him in elite company. Since 1901, only 21 batters have ever broken 10 WAR in a season, and all of them either are in the Hall of Fame, would be in the Hall of Fame if not for allegations of performance-enhancing drug use (Barry Bonds and Sammy Sosa) or are currently active (Trout). Betts is also putting on a tour de force in all-around ball-playing: On a rate basis, his season is one of only nine since 1913 in which a qualified batter ranked in the 80th percentile or higher in contact rate, walk rate, isolated power, base-running runs and defensive runs above average.

Mookie is having an all-around season for the ages Qualified seasons in which a batter was in the 80th percentile of MLB in contact rate, walk rate, isolated power, base-running runs and defensive value (adjusted for position), 1913-2018 Percentile Rank in… Player Year Team Contact% Walk% Iso. Power Base Running Defensive Value Mookie Betts 2018 Red Sox 89 89 98 96 83 Ian Kinsler 2011 Rangers 95 92 89 88 87 George Brett 1980 Royals 98 82 99 88 86 Fred Lynn 1980 Red Sox 80 87 82 80 82 Joe Morgan 1975 Reds 82 100 88 97 91 Joe Morgan 1973 Reds 82 95 91 95 86 Stan Musial 1944 Cardinals 87 91 96 89 85 Tris Speaker 1919 Indians 98 91 91 82 81 Tris Speaker 1914 Red Sox 97 84 96 92 82 Defensive value includes positional adjustment, so more difficult/valuable positions get more credit. Sources: Baseball-Reference.com, FanGraphs.com

Ordinarily, an individual season as brilliant as Betts is having — on a team as dominant as Boston has been — would almost automatically guarantee an MVP.

But things have gotten a little complicated recently, as Martinez’s candidacy has been picking up more and more steam. Martinez has a 1.038 OPS this season, and he now ranks seventh in the AL in WAR. More importantly for his MVP case, Martinez also currently sits second in baseball (behind Betts) in batting average, second (behind Khris Davis) in home runs and first in runs batted in.

If he climbs to No. 1 in each category, Martinez would become the first player since Mickey Mantle in 1956 to win the MLB-wide Triple Crown: leading both leagues in average, homers and RBI. Miguel Cabrera famously won the AL Triple Crown in 2012 — the first in baseball since 1967 — and the cachet helped him win the MVP over Trout despite a sizable edge for Trout in WAR.

For MVP voters with a traditional approach to the award, that type of feat would be impossible to ignore, regardless of how great Betts has been. So we could be looking at another referendum on the relative importance of an all-time great WAR season versus greatness in some of the oldest measurements in the book. Pair that with an NL Cy Young race that promises to test voters’ age-old allegiances to pitcher wins, and baseball’s award season should have plenty of nerds-vs.-fogies intrigue this year.

Of course, Martinez still has a lot of work to do to grab the lead in each Triple Crown category. And given some of the recent changes in how award voters view the game, a 10-WAR performance from Betts could carry the day even if Martinez pulls off the old-fashioned feat. Both Red Sox sluggers also still need to hold off potential late MVP surges from Trout or Indians third baseman Jose Ramirez, who’s also enjoying a historically great season. But the potential is there for this award chase to be epic, pitting teammate against teammate and old stats against new ones.

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