It seems like a long time ago, because it was: Last May 25, Florida's Scott Cousins tagged up on a fly ball and, at the last possible split-second, changed course and destroyed San Francisco's Buster Posey.

Specifically, Cousins destroyed Posey's left leg, shattering bones and rupturing ligaments and tendons and this yucky gristle that doctors still haven't given a name.

Posey's season, of course, was over. And so, essentially, was the Giants' season. SI.com's Joe Lemire:

Backups Eli Whiteside, Chris Stewart and Hector Sanchez combined to hit .205 in 378 at bats, with just a .276 on-base percentage; if those rate stats had been for an entire season, the average would have ranked last in the NL and the OBP would have been second-to-worst.

Talk of being ready for Opening Day -- San Francisco starts its season on April 6 in Arizona -- certainly seems realistic if his Cactus League debut goes as planned, but it's too early to make definitive proclamations. What can be said for now is that Posey has adhered to his rehab program and put himself in good shape to be ready for spring training, so he can see how the ankle responds to the unpredictability of game situations as opposed to the controlled environment of workouts.

"There's really no way to know," he said. "You've got to get out there and do it."

When -- and how well -- he does it might very well determine the Giants' season.

Remember, Posey got hurt in late May. He's really good. His backups were really bad.

Actually, they weren't really bad. They were just catchers. Whiteside and Stewart and Sanchez were actually a little better than ... well, not league average. Not even close. But they were a little better than replacement level. All things being equal, Posey's absence probably cost the Giants roughly four wins. But it might be three and it might be five. And that's even ignoring clutch hitting, etc.

If the Giants had won four more games last season, they would have tied the Cardinals for the Wild Card, and then who knows what might have happened? But you might reasonably argue that when Scott Cousins destroyed Buster Posey's left leg, he also gave the Cardinals the World's Championship. In a roundabout sort of way.

Lemire's right: The same thing might happen this year, with Posey's performance (or not) being the difference between the Giants playing in October or not playing. Of course, this is the case with every star player on a team that figures to be in a close race for a division title or Wild Card. Most of the time we would generally assume the player would be healthy, and return to roughly his previous level of performance. But a catcher whose ankle and knee were shredded?

Leaving aside pitchers coming back from serious arm injuries, Buster Posey is the single player most worth watching in March. Because as he goes, so the San Francisco Giants probably go.