The first Yankees-Red Sox matchup of 2018 is happening tonight, and ordinarily, we’d be full of anticipation over one of the best seasons in memory for the historic rivalry.

And yet, between injuries and early-season slumps, a bucket of cold water has been splashed on each team’s start of the season. The Yankees come into the game with a disappointing 5-5 record, headlined by the well-documented struggles of right fielder Giancarlo Stanton — who has turned into a $25 million strikeout machine. And the biggest factor driving Boston’s early success hit the disabled list Monday, as shortstop Xander Bogaerts injured his ankle Sunday sliding into the dugout after a stray ball. Because of these setbacks, we might not see the best the Red Sox and Yankees have to offer until later in the year, with this week’s games merely serving as previews for the true battles to come.

Stanton’s problems were on display Sunday, when he had his second five-strikeout performance of the season, this time against the Baltimore Orioles. In the process of earning that platinum sombrero, Stanton became only the third player in MLB history to post multiple five-K games in the same season (joining Ray Lankford of the Cardinals in 1998 — who had three such games — and Deron Johnson of the Reds in 1964). The difference is that it took both Lankford and Johnson months to get rung up so many times in separate games; for Stanton, it took exactly 11 days. (Not to mention that Lankford and Johnson were not reigning National League MVPs.)

His whiffs might have also earned Stanton the record for the quickest descent from fan adoration to full-on boo birds at Yankee Stadium, even adjusting for the notorious pressure-cooker that is baseball in the Bronx. Obviously, Yankees fans need to collectively take a timeout and walk around the block — Stanton is sure to regress back to some version of his established norms before long. But Stanton does appear to be a little out of sorts these days. So far this season, he’s swinging at more pitches outside the strike zone than he did last year. He’s getting in favorable hitter’s counts less often. He’s making much less contact, whiffing especially often on pitches inside the zone. And in an era of uppercut swings, Stanton’s swing is flattening out: He’s down to an average launch angle of 10.6 degrees this year, continuing a three-year dip in the metric.

Of course, Stanton used only a barely steeper swing plane to bash a career-best 59 home runs last year, even flirting for a while with Roger Maris’s pre-steroids-era record (61) for homers in a season. And Stanton’s average exit velocity is higher this year than last. So it’s a good bet that Stanton will eventually settle down and start delivering on the big expectations that followed him from the Marlins to the Yankees. The question is when — and whether it will come against a Red Sox staff that ranks second in the majors in fielding independent pitching.

Speaking of the Sox, before Sunday, finding faults in their MLB-leading 8-1 start to the season was difficult. But without Bogaerts, Boston is down its best hitter this season just as the archrival Yankees are arriving in town. According to the Red Sox, Bogaerts is expected to miss up to two weeks with the ailment. It’s not a severe injury, but it comes at the worst possible time for the budding star.

Bogaerts has long been one of the most tantalizing players in baseball, a shortstop with the bat skills to potentially hit .300 and the power to mash 20 homers. But even though he has enjoyed a fine run over the past three seasons and change, he hasn’t quite put everything together in the same season like, say, Houston’s Carlos Correa was able to last year. Just like Stanton in New York, Bogaerts has been a victim of both his own talent and the expectations that come from playing under the microscope of an insatiably baseball-crazed fan base.

In the first week-plus of this season, however, Bogaerts appeared to be enjoying the breakout season that Boston fans have been waiting for. Not only was he leading all Red Sox players in wins above replacement, but he also ranked seventh in all of baseball (including hitters and pitchers) in the statistic. If he were to have more games like the six-RBI performance he produced against the Rays on Saturday (which included this mammoth grand slam over the Green Monster), Bogaerts would have been building the foundation for a potential MVP-type season. Now, his absence leaves a hole in the middle of Boston’s lineup.

Of course, the Red Sox still have Mookie Betts, J.D. Martinez, Rafael Devers and even the resurgent Hanley Ramirez. They also have that stingy pitching staff, led by Tuesday’s starter, ace Chris Sale (who’s off to another Cy Young-caliber season with a 0.82 ERA in his first pair of starts). There’s plenty of talent on both sides going into this initial Boston-New York skirmish.

In fact, according to our Elo ratings (a rolling estimate of each team’s quality over time), this is among the best the teams have ever been going into their first meeting in a given season (and the best since 2010):

How this year is shaping up for the Yankees-Red Sox rivalry Best Elo ratings for the Yankees and Red Sox (based on harmonic mean of two teams’ ratings) going into their first matchup of the season, 1901-2018 Elo Ratings Rk Season Date Yankees Red Sox Harmonic Mean 1 1978 June 19 1548 1568 1558.2 2 1951 April 17 1565 1550 1557.7 3 1950 April 18 1554 1560 1556.9 4 1943 April 25 1569 1545 1556.7 5 2000 May 26 1559 1554 1556.7 6 1940 April 26 1584 1528 1555.5 7 1949 April 22 1558 1548 1553.0 8 2010 April 4 1569 1537 1552.9 9 1942 April 17 1568 1537 1551.9 10 1939 April 20 1566 1535 1550.5 11 2005 April 3 1537 1564 1550.2 12 2003 May 19 1563 1536 1549.1 13 1998 May 22 1577 1521 1548.5 14 1986 June 16 1550 1546 1547.9 15 2018 April 10 1549 1547 1547.7 16 1979 May 18 1546 1548 1547.2 17 2008 April 11 1536 1558 1547.1 18 1952 April 23 1557 1535 1546.0 19 1999 May 18 1559 1531 1544.6 20 2009 April 24 1533 1551 1541.9 The harmonic mean helps identify pairs where both values are high, which lets us weed out pairs where only one team was very good and the other was bad.

Still, there’s a good chance that we won’t see that true potential emerge until we get deeper into the two teams’ 19-game head-to-head slate. Bogaerts will return soon enough, and Stanton will surely get comfortable and go on a home run tear at some point. Last season’s Red Sox-Yankees matchups were the most meaningful they’d been in a dozen years — in terms of influence on the pennant race — and this year’s crop could be even more consequential, given the aforementioned Elo ratings and the projected closeness of the AL East race. This week’s series is just the beginning, a sneak peek for what still ought to be the summer’s most compelling tug-of-war.