Throughout the late 1990s, the Yankees won three World Series in a row and came within two outs of a fourth with much of the same cast of characters. In fact, 14 players on the 2001 team were also on the 1998 team, and other than the DH spot, the regular 1998 starting lineup took the field during 2001.

This stability makes the Yankees unique among World Series winners. Most, according to a Jonah Keri article in The Times this weekend, turn over 28 percent of their roster — or approximately seven players — after winning. These moves make teams better, younger and more able to maintain a competitive edge, and the current iteration of the Yankees would do well to heed Keri’s warnings.

First, some numbers. Keri used the introduction of the Wild Card as a baseline, and he found that six of the 13 World Series winners, not counting the 2009 Yankees or the extreme outlier 1997-1998 Marlins, turned over less than a quarter of their rosters and combined to lose 47 games — or nearly eight per team — more than they had in their World Series years. Those teams that turned over more than 25 percent lost just three combined games more the following year. Clearly, a savvy general manager along with some roster machinations can lead to repeated success.

For the Yankees, Keri’s lessons are particularly apt:

The Yankees face another regression-related situation. They had an old roster in 2009. Two of the top three starters, five of the nine starting batters as well as the Hall of Fame closer were 33 or older.

It is possible that 35-year-old Hideki Matsui’s knee problems are behind him and that 28-homer seasons will remain the norm. It is conceivable that Johnny Damon’s tying a career high for homers at 35 (he turned 36 on Nov. 5) means we should expect a big power threat for the next half-decade. It is imaginable that Andy Pettitte, a 15-year veteran who has flirted with retirement in recent years and has nearly 3,000 regular-season innings under his belt, will keep winning games well into his late 30s and beyond.

But it is not likely. Few players are more likely to see a regression in their numbers than those getting well into their 30s who have suddenly had a big bounce-back season. The Yankees caught lightning in a bottle with Matsui, Damon and Pettitte, who are free agents, as well as incumbent 30-somethings like Jorge Posada. Even (gasp) Mariano Rivera cannot fight Father Time forever.

The Yankees, warn Keri, shouldn’t grow complacent, and by extension, neither should the fans. It would, in fact, be foolish for the Yankees and their fans to claim this team can repeat what it did last year without questioning some holes. To that end, the Yanks should look to free agency to boost the team. A few younger bats are out there, and some hurlers who could replace Andy Pettitte loom as well.

But there is a part to Keri’s thesis that he didn’t explore in his column. I e-mailed Jonah today to ask him about the so-called sentimental players who have won over fans by winning a World Series: What if the ‘sentimental guys are 1) on short term deals and 2) are better than other options on the market?

Jonah’s answer was not surprising. “You definitely want to go with incumbents if nothing better is out there,” he wrote. “Of course, something better clearly is out there, between Holliday and Bay, plus maybe some trade candidates. So yes, it could very well be a question of deciding whether, say, Damon at 2/28 is better than Holliday at 7/120. There’s no easy answer to that one – you’d probably just go for the better (and younger) player, since the Yankees can obviously afford it.”

The Yanks can afford Holliday today, but do they want to be paying him in four or five years? That’s the real rub, and the answer is “probably not.”

Oftentimes, good teams are, in part, the product of career years and a good deal of luck. With their walk-off wins and overall season numbers, the Yanks certainly exhibited a combination of the two in 2009. To avoid a fall, expect some roster turnover. If the incumbents can be had for cheap and the big fish sign elsewhere for too much money, as Keri said to me, the Yanks would be golden, and that right now is in the hands of the Front Office.