A year and a half ago, when Johnny Damon was a free agent, one of his main assets was his durability. His agent, Scott Boras, liked to tout some odd statistical arcana to prove this point. From 1980 through 2005, for instance, Cal Ripken Jr. was the only player other than Damon to play 130 games every year for a decade without going on the disabled list. Using these sorts of arbitrary endpoints makes Damon look more unique than he is, but the basic point was true: He’s exceptionally reliable, and that makes him exceptionally valuable. A player who hasn’t been injured in the past is far less likely to be injured in the future, and a player who doesn’t get injured is one who spares his team from having to play the green youngsters and minor league journeymen who end up filling in when a player goes on the DL.

Yesterday’s news that Damon may have to go on the disabled list with a strained calf, then, is not only surprising, but plain bad news, for now and the future. Damon is a very good all-around player, but not a brilliant one. Much of his value to the Yankees is tied up in how much he plays rather than how well, and even how well he plays is tied up with his speed, on which he relies for defense and batting average as well as baserunning. A muscle strain is of course just a muscle strain, but Damon is 33, not really young for a ballplayer, and if he loses his legs, he’ll be an adequate player, not a star.

Fortunately for Yankees fans, there is some good news to accompany the bad: Melky Cabrera will be starting until Damon is ready to play. That’s good because the 22-year-old is a fine player in his own right, and because he isn’t Bernie Williams. On both counts his presence on the field tonight will offer proof that the Yankees really have changed the way they do business over the last few years.

Over the winter, about four dozen variations on a trade that would have sent Cabrera to Pittsburgh for left-handed reliever Mike Gonzalez were rumored, most involving an intermediary. This would have been a reasonable if risky deal for the Yankees; Gonzalez is an excellent pitcher, the shutdown eight-inning man the team presently lacks. Cabrera, though, has immense potential. A 21-year-old who can handle center field, walk as much as he strikes out, and get on base 36% of the time at Triple-A is valuable; Cabrera did that in the majors last year. If he never becomes a power hitter, he’ll still likely have a few All Star caliber seasons, and he has a decent chance of developing into a player on par with Williams or Carlos Beltran.

As obvious a move as it might be to hold on to a player like this, it’s not what the Yankees would always have done. A setup man like Gonzalez really could mean the difference between winning or not winning the World Series, and given some of the trades the Yankees have made over the past decade, it’s not difficult to imagine them exiling Cabrera for a far less valuable pitcher.

There’s a difference between not exiling someone and giving them a real shot to play, though, and that’s perhaps the most impressive thing here — that Cabrera was given his 460 at-bats last year, and that he’ll probably end up with close to that many this year. Over the past several years, the Yanks have hauled in every nostalgia act on offer. Tino Martinez, Jeff Nelson, Mike Stanton, Ruben Sierra, Rey Sanchez, Ramiro Mendoza — there have been times recently when I expected to hear that Cecil Fielder would be coming up to the plate. And of course there were the 2,000 or so plate appearances Williams got even after it became clear he was no longer capable of playing center field.

Williams’s day is done — when general manager Brian Cashman was asked if a Damon injury might open a spot for the beloved old man, he simply said, “No.” It’s a sad story; Williams still wants to play ball, and only for the Yankees. Cashman looks a bit heartless when he says that time has passed. Heart, though, doesn’t help anyone win titles when it takes the form of squishy sentimentality. Titles are won when someone has the guts to own up to the fact that Cabrera needs his at-bats more than the Yankees need to show loyalty to a player whose days as a star ended five years ago. Damon will be back soon enough, and Cabrera will go back to the bench to await his turns to play, which will come on this veteran team. Even as he awaits his day, though, his mere presence will show that Yankee capos are at last more concerned with what someone is capable of doing in 2007 than with that they did in 1997. If they remain so, the team can’t be stopped.

tmarchman@nysun.com