The shame of Derek Jeter’s career is, basically, that he’s Derek Jeter. At 32, an age when most star ballplayers are notably declining, he’s having probably the best season of any player in the American League and the second-best season of his entire career, and yet the main story line of his season has revolved around fan reactions to Alex Rodriguez.

Jeter’s many years of being Derek Jeter have taken their toll on public perceptions in two ways. The first is that his decade of refusing to say anything at all interesting has, while lending him an aura and mystique unrivaled by any contemporary other than perhaps David Ortiz, naturally has inspired a fair amount of Kremlinology; a slight grimace while discussing the fans’ silly and self-defeating treatment of Rodriguez can inspire hours of drivetime ranting.

The second is that so many inflated claims have been made for his ballplaying prowess that when he is having a truly magnificent season, the praise comes off as hollow. If his intangibles, after all, have made him the best player in baseball as a .290 hitter and indifferent defender, what is he as a .350 hitter and vastly improved defender? The best player of all time? The vocabulary isn’t quite there to describe what he’s doing. In the realm of praise, good currency drives out bad.

This is too bad, because Jeter deserves all the praise New York can muster this season. We’ll see how things play out — Ortiz’s monstrous clutch performances are a great argument on his behalf, and if the Red Sox beat out the Yankees for the division that argument will be still stronger — but right now, Jeter is the league’s MVP, and you don’t need to give him an ounce of credit for either aura or mystique to tell it’s so. Compared with hitters at his position, he’s a more effective offensive player than anyone else in baseball, and he’s playing shortstop. That’s his case, and it’s backed up by the numbers. What’s a bit more interesting is how he’s doing it.

Qualitatively, Jeter isn’t doing anything much different this year than he always has done. His hands seem a little bit quicker, his swing’s slightly more level, and he’s serving the ball into shallow left a little bit more than he usually does, but there hasn’t been some radical change in his approach. He’s hitting essentially how he always does, just a bit more so or less so.

He’s not hitting essentially what he always hits, though, which is the difference. He’s on pace for 14 home runs, which would be his lowest full-season mark since 2000; and for 40 doubles, which would be the second-highest total of his career and vastly above his established level of 25 or so (a total he’s already exceeded); and of course that .348 average is 32 points above his already excellent .316 career mark. So what gives?

Digging a bit deeper into the numbers, there are a couple of substantial changes — not huge ones, but notable ones. His groundball to flyball ratio is 3.28, a very high mark by his standards — it’s more than twice his 2004 ratio, for instance.He’s also striking out much less than he usually does, in just 15.4% of his at-bats, and thus posting a strikeoutwalk ratio identical to the one he put up in 1999, the best year of his career. There’s a chicken-and-egg question here: Does his high average drive those ratios that show an improved batting eye, or does the improved batting eye cause the high average? But the overall picture is of a slightly more patient Jeter swinging a bit less for the bleachers.

What’s unusual about this is that of course most 32-year-olds show just the opposite pattern. They show improved batting eyes, improved power, and lessened ability to place the ball, which you’d naturally expect because as players age, their reflexes begin to slow, and they begin to rely more on their knowledge of the game than their physical skills. Why is Jeter an exception?

I think we’re seeing a bit of development in Jeter — the one flaw in his offensive game has always been his habit of overswinging.This reminds us that baseball is not a linear game. Tiny changes in a batter’s approach can have enormous consequences.That slight bit of improvement in Jeter’s ability to yank the ball has an impact on his overall game, in everything from how often he puts the ball in play to how often he pops a double into the left-center gap.

That slightly more level swing influences everything from how often he hits the ball in the air to how often it goes over the fence when he does. These things can make the difference between an exceptional player having his usual exceptional season to having an MVP-level year. It’s not someone stepping his game up because the guy to his right is having a down year; it’s a great player changing in his baseball middle age, and it’s fascinating enough in its own right without turning a ballplayer into the Sphinx.

tmarchman@nysun.com