I was stunned to learn that Derek Jeter had never won a game with a walk-off homer prior to yesterday’s killer off Keith Foulke. I figured that along with healing the sick, walking on water, and dating Jessica Alba, hitting such a homer would be the least of his accomplishments. And when you add all up all of the above, is it really so damning that Jeter is such a mediocre fielding SS?

Like me, the Bergen Record’s Bob Klapisch loves finding fault in those who are seemingly infailable. Except he’s actually good at it.

It was a Game 7 moment, tightening Derek Jeter’s spiritual hold on this team. He took Keith Foulke over the right-field wall, a perfect moment of opposite-field power that propelled the Yankees to a dramatic 4-3 win over the Sox. Teammates didn’t just celebrate with Jeter, they practically partied with him, underscoring just how important April is to the year-after Bombers.

As hard as they tried, though, there was no burying the reason the Yankees leaned so hard on Jeter. The images of Mariano Rivera’s collapse in the top of the ninth were still there, if not at home plate, then in the postgame clubhouse as the closer tried to make sense of Jason Varitek’s game-tying home run in the top of the ninth.

The time-tunnel replay was almost too much for the Yankees to comprehend, considering it was Rivera’s failure in Game 4 of the AL Championship Series that started the greatest collapse in postseason history. Rivera couldn’t finish off Boston last October, and he was just as ineffective on Tuesday.

Are the Yankees worried? No one will dare admit it, even though Rivera has blown three straight saves to Boston and five of his last 10. Rivera is just as sanguine, only saying, “I blame myself for throwing the ball in a bad spot” to Varitek.

But after surrendering Bill Mueller a single to center and striking out Mark Bellhorn, Rivera was nearly bludgeoned by Johnny Damon, too, allowing a fly ball that took Gary Sheffield to the wall.

Rivera watched in apparent disbelief as the third out finally landed in Sheffield’s glove. For several seconds, the closer stood frozen, half-bent like a question mark: How could he have missed with fastballs that were supposed to be up and in, but instead strayed suicidal over the plate? Manager Joe Torre keeps insisting he has an unshakable faith in Rivera. So do the rest of the Yankees. But, clearly, something’s wrong.

The first theory is the most obvious: Rivera is 35 and showing increasing signs of his own mortality. Rivera’s velocity is still well above average at 92-94 mph, but he’s already experienced a bout of bursitis in his right elbow this spring.

Even more telling is the loss of pinpoint control within the strike zone, especially with his cut-fastball. Instead of consistently lasering into a left-handed hitter’s hands – Atlanta’s Chipper Jones once likened the pitch to a “buzz saw” – Rivera’s cutter sometimes drifts into the heart of the plate.

When that happens against the Red Sox, it’s a recipe for ninth-inning heartbreak. Torre conceded, “Unless you pitch to those guys perfectly, they’re dangerous. To me, it’s all about location.”

The other theory is that, even if Rivera was as precise as a surgeon, he’d still be paying the price for overexposure against the Sox. Some of their hitters have accumulated so many career at-bats against Rivera, they’ve more immunized to the speed, action and location of Rivera’s cutter.

How else to explain why Manny Ramirez (29 at-bats) Damon (20), Varitek (18) and David Ortiz (10) can look comfortable against the greatest closer of this generation? After his game-tying home run, Varitek explained that while, “I wasn’t able to get all of [the cutter]” Rivera nevertheless missed badly enough to cost Carl Pavano a win in his American League debut.