Ever since the Red Sox and Yankees staged their epic clash in the 2004 ALCS, the teams have been on a baseball see-saw.
When the Red Sox have been up, the Yankees have been down. And vice versa.
Last season, when the Sox went on their improbable ride to become 2013 World Series champs, the Yankees -- though they admirably stayed in contention until the final 10 days despite an injury-decimated lineup -- missed out on the postseason for the first time since 2008.
And the last time the Yankees won a World Series in 2009, the Red Sox were swept out of the Division Series in three games, beginning a downward slide that saw them miss the playoffs altogether for each of the next three seasons.
Whether they like to admit it or not, the two franchises often respond to the other's success. After its 2008 failure -- during which time the Sox came within an inning of reaching their second straight Series -- New York spent with abandon that offseason, signing CC Sabathia, A.J. Burnett and Mark Teixeira. And when the 2010 Sox completed their straight season without a postseason victory -- and the Yankees were, correspondingly, winning a World Series and a division title -- they responded by heaping big deals upon Adrian Gonzalez and Carl Crawford.
But now it seems like less of a see-saw and more like divergent paths.
The Yankees remain the Yankees: They responded to the Red Sox' 2013 championship by gorging themselves at the free-agent buffet this offseason, signing Carlos Beltran, Brian McCann, Jacoby Ellsbury and Masahiro Tanaka. But the Sox have adopted a more reasoned approach to roster-building: shorter-term deals to fill immediate needs with a steady integration of in-house prospects, the likes of which the Yankees can only envy.
Those contrasting styles will be on display Thursday night in the teams' first meeting of the season . . . the start of a stretch that will see them play 7 times in 15 days.
Unsurprisingly, given the star power of the two brands, all four games will be shown nationally: the first two on the MLB Network, Saturday's matinee on Fox Sports 1 and Sunday's series finale on ESPN.
But media fascination aside, is this the year the rivalry rediscovers its juice?
The series begins with both teams a game under .500 and dealing with early-season injuries. The Yankees are already missing closer David Robertson and first baseman Mark Teixeira, while the Red Sox are without third baseman Will Middlebrooks and right fielder Shane Victorino.
Having imported McCann, Ellsbury and Beltran, the Yankee offense -- which finished 10th in runs scored in the American League last season and 13th in OPS -- has to be better. But major questions remain about the team's infield, especially on the left side, where 40-year-old Derek Jeter and Kelly Johnson hardly inspire confidence.
The bullpen, too, appears thin. Even if Robertson proves adequate in the closer's spot, getting to him with a lead in the ninth could be problematic given the set-up crew.
And there's this: for a host of reasons, the Yankees aren't the dominant team they were a decade ago.
Baseball's landscape has changed; revenue sharing has leveled the playing field like no other time in the free-agent era. Now, when the Yankees flex their financial might to sign top free agents, it's less a show of their dominance and more a sign of desperation.
While other clubs, large market and small alike, build consistent winning teams through a mixture of homegrown players and shrewd trades, the Yankees seem like an anachronism, chasing the few big aging stars still on the free-agent market and lavishing them with overly long contracts.
It's as if the rest of baseball is operating in an era of digital downloads and the Yankees are proudly showing off their top-of-the-line Betamax.
For all their free-wheeling spending, the Yankees can't even claim to have the game's biggest payroll. That honor is held by the Los Angeles Dodgers, who, armed with a record-setting TV deal, seem intent on copying the Yankees' obsession with star players, for better or worse. But the Dodgers and Yanks stand alone; the plaudits they earned for last year's success indicate that the Red Sox are the franchise most other teams are trying to emulate.
You get the sense the two organizations are playing by very different rules that go far beyond payroll disparity (the Yankees will outspend the Red Sox by more than $60 million this season). Given that the Red Sox have won three World Series to the Yankees' one since 2004, the Sox no longer apologize for the gap.
(Even the Yankees nearly got a dose of fiscal restraint, as, for the last several years, owner Hal Steinbrenner vowed to stay under the luxury tax threshold in 2014. That lasted only until tempting baubles such as Masahiro Tanaka appeared before them, at which point the Yanks seemed to shrug and exclaim: "Oh, what the hell . . . ")
That the Red Sox no longer seem intimidated by the Yankees' once-formidable economic advantages means they no longer carry the sport's biggest chip on their shoulders. Winning three titles will do that.
All of which means this series will, aside from the Jacoby Ellsbury angle, be lacking in juicy storylines and will be little more than Just Another Series.
Of course, if the teams should again collide in October, all bets are off.