Mariano Rivera is helped off the field by Yankees manager Joe Girardi (right) after injuring his right knee. (AP)
The other day at Yankee Stadium, the subject on the table was starter vs. closer.

Would you rather have a true No. 1 starter or a great closer?

The baseball people around the table said starter.

I said, "What if the closer is Mariano Rivera?"

"That's different," they said.

Exactly.
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The Yankees might be the team most equipped to handle the loss of a closer. And the least.

The most, because David Robertson is a closer-in-waiting, already the best eighth-inning man in the business. The least, because there's only one Mariano Rivera.

The news that he was diagnosed Thursday night with a torn ACL hits the Yankees hard. It hits baseball hard, because Rivera is 42 years old and has hinted that this could be his last season.

A torn ACL would likely cost him the rest of this season. It's far too early to know for sure if that would push him closer to retirement or further from it, but even the possibility that we've seen the last of Rivera closing games for the Yankees is hard to take for anyone who loves this game.

Rivera has never been hated, only respected. All of us who watched him -- Yankee fan and Yankee-hater alike -- understood that we were watching the greatest closer ever.

But Rivera has been more than just the best closer ever.

He has dominated his position more than anyone in the history of the game has dominated any position.

"Someone else can do his job," Derek Jeter told reporters. "But you can't really replace him."

You could argue, as Tiger manager Jim Leyland often has, that Rivera was the most valuable player in all of baseball from 1998-2000, when the Yankees won three straight World Series. In three straight Octobers, Rivera went 18-for-18 in save opportunities, with a 0.65 ERA.

That was incredible, but so is this: In 18 years with the Yankees, in a role where most have a roller-coaster existence, Rivera never had a bad season. His highest ERA since becoming a reliever was 3.15; his lowest save percentage was 83, and he was almost always at 87 percent or higher.

That was incredible, but so is this: In a business where closers seem the most fragile of players, Rivera has gone nine years since his last trip to the disabled list.

Even now, he wasn't hurt on the mound. He was hurt shagging fly balls during batting practice, trying to catch a fly ball hit by Jayson Nix and slipping on loose dirt on the warning track.

You can't second-guess him for shagging, because he has done that his entire career. He looked so good doing it that one of his minor-league managers called him the best outfielder on the team.

You believed it, because you would believe Rivera could do anything. He survived year after year throwing just one pitch, a cut fastball.

No, that's not right, because he didn't survive. He thrived. He did it when he was 26, and he was still doing it at 42.

We've never seen anyone else like him.

And all of us -- not just the Yankees and their fans -- can only hope now that we haven't seen the last of him.

It has to end sometime.

It shouldn't end like this.