Since the New York Yankees’ incredible five-year run at the end of the last century, which saw the club win four titles with a youth-filled core, the Yankees have long been seen as an aging group of veteran free-agent purchases. Jason Giambi, Mike Mussina, and Alex Rodriguez supplemented Derek Jeter, Jorge Posada, Bernie Williams, Andy Pettitte, and Mariano Rivera as the group entered their 30s. Whether that perception was fair or merely irrelevant, the club remained successful for much of the last decade as players aged slowly and made great contributions into their 30s. As Major League Baseball got younger, though, the Yankees’ core aged without young replacements on the farm. It appeared as though the Yankees might have a rough couple of years when, after the club missed the playoffs in 2013, ownership tried to reduce payroll below $189 million in attempt to save millions in salary cap money and revenue sharing.

As sometimes happens, though, the Yankees’ owners appeared to change their mind and a spending spree in the winter of 2013 brought in free agents Jacoby Ellsbury, Brian McCann, and Carlos Beltran, as well as the acquisition of Masahiro Tanaka in order to compete in 2014. That effort fell short as injuries, age, and the missing production of Alex Rodriguez all took their toll on the franchise and the team fell short of the playoffs. In 2015, the team’s elder batsmen — Mark Teixeira, Alex Rodriguez, and Carlos Beltran — have remained healthy for much of the season and led the way for an offense sporting a 107 wRC+, second only to the Toronto Blue Jays in the American League.

Mark Teixeira had been having a phenomenal year prior to his recent injury, Alex Rodriguez has been strong in his return from suspension, and Carlos Beltran has recovered nicely from a very poor start to the season. All three are among the very best in the league among position players 35 years old and older this season.

Best 2015 Seasons by Players at Least 35 Years of Age Name Team AVG OBP SLG wRC+ WAR Age Mark Teixeira Yankees .255 .357 .548 145 2.9 35 Adrian Beltre Rangers .273 .314 .427 96 2.7 36 Alex Rodriguez Yankees .257 .363 .489 133 2.3 39 David Ortiz Red Sox .264 .352 .515 128 1.9 39 Albert Pujols Angels .247 .305 .493 121 1.8 35 Juan Uribe Braves .254 .318 .418 103 1.7 36 A.J. Pierzynski Braves .293 .333 .424 107 1.7 38 Carlos Beltran Yankees .282 .344 .480 125 1.6 38 Matt Holliday Cardinals .290 .409 .420 132 1.2 35

The above list constitutes every player 35 and older with at least one win above replacement on the season. Just a decade ago, there were double that amount, and two previous years had a dozen players each. The Yankees and the Philadelphia Phillies are the only teams with more than 1,000 plate appearances from players at least 35 years old, and the Yankees’ 6.8 WAR from those players is more than double the second-place Braves — and actually higher than the rest of MLB combined (6.6 WAR).

The presence of a few older players might represent an interesting side story, but the Yankees are not just older at the outer reaches of their roster. Almost every one of the Yankees’ key contributors on the position-player side is over 30 years of age. They have a fairly young pitching staff, with Tanaka, Michael Pineda and Nathan Eovaldi leading the staff, but of the players with more than 200 plate appearances, only Didi Gregorius is under 30 years old.

New York Yankees: 2015 Statistics and Age (By PA) Name PA wRC+ Def WAR Age Brett Gardner 536 116 -5.7 2.7 31 Chase Headley 514 106 2.7 2.5 31 Alex Rodriguez 501 133 -12.3 2.3 39 Mark Teixeira 462 145 -8.5 2.9 35 Didi Gregorius 454 86 9.4 2.0 25 Brian McCann 427 116 9.5 3.2 31 Carlos Beltran 398 125 -8.5 1.6 38 Stephen Drew 391 79 0.4 0.3 32 Jacoby Ellsbury 373 102 -0.8 1.5 31 Chris Young 303 110 -3.4 1.2 31

Off the list, the Yankees’ backup catcher J.R. Murphy has over 100 plate appearances, and 22-year-old Greg Bird has gotten a chance at first base with Teixeira down, but he still needs another couple weeks to crack 100 plate appearances for the season. It should come as no surprise, given the success of the offense and the team, that the Yankees lead the majors in WAR from players 30 and older.

Historically, what the Yankees are doing is not that significant. From 1996 to 2010, 25 teams had at least 20 WAR from players at least 30 years old. The previous four seasons have seen just two such teams: the New York Yankees of 2011 and the Boston Red Sox of 2013. There were no teams last season above 20 WAR, but at 17.2 so far this season, the Yankees have a decent shot at cracking that barrier. Not only is their cumulative WAR tops in MLB, the percentage of position player WAR from players 30 and older is also ahead of the rest of baseball.

Only five teams have more than 50% of their position player WAR coming from older players, but for the Yankees, that number exceeds 90% while the second place Seattle Mariners come in around two-thirds this year. It has become more and more difficult to find good players in their 30s, but through spending in free agency and decent health, the Yankees have a good share of that market. That market is unlikely to remain robust as players age. The graph below shows the overall WAR of players by age group.

The difference in WAR between the before-30 and after-30 group is mostly accounted for by playing time with the under-30 group accumulating 64% of the plate appearances this season. However, the difference in playing time does not account for the entire difference as 73% of the WAR has been accumulated by players under 30 years of age.

Weighting all plate appearances this season by age, the average seasonal age per plate appearance is 28.5 years old. The Yankees are well above that mark at nearly 32 years of age. The graph below shows the average age per plate appearance for every team with pitchers excluded.

The difference between the first-place Yankees and the second-pace Cincinnati Reds is greater than the distance between the Reds and the 25th-ranked Pittsburgh Pirates. The Yankees were more than three standard deviations from the mean with only the Astros on the other end of the graph barely more than two standard deviations away from the mean.

The Yankees are relying on a late-90s, mid-2000s formula for success this season, and for the most part, it has worked. The team looks to be on their way to close to 90 wins, and the FanGraphs playoff odds virtually assure the team of a playoff spot. The strategy is unorthodox and few teams could even attempt to pull it off, but with the Yankees resources, they can cover up developmental deficiencies. It might not work next year, but right now, the Yankees look poised to end their playoff drought on the back of older roster.