If he ever hits it — and he may not, if he persists in trying to drive every pitch that nears the plate through the outfield wall — Alex Rodriguez’s 500th home run will not, and will not be taken as, any sort of crowning achievement. Merely great players hit 500 home runs. Rodriguez is something else.

How to put this accomplishment in perspective? It’s difficult to do. Consider that Jimmie Foxx, heretofore the youngest man to hit his 500th home run, was about a month away from turning 33 when he did it; Rodriguez turned 32 last Friday. Another way to put it is this: As is well known, Rodriguez is far ahead of Hank Aaron’s pace. He’ll probably have around 520 home runs at the end of the season; Aaron, at the same age, had 398. Rodriguez is also ahead of Barry Bonds’s pace, as Bonds had 334 home runs at this age. The gap between Rodriguez and Bonds will thus likely be around 186. Derek Jeter has hit 191 home runs in his career.

With all of this being so, the natural question is, “How many home runs will Rodriguez hit?” Certainly, barring injury, he has an excellent chance of breaking what will by then be Bonds’s record, and thus of being the object of the kind of adulation he so seems to desire and has been denied in his career. In those days, no one will call him out for limping toward home run number 500 with an ill-timed 0-for-19 streak. He’ll be hailed as the savior of baseball, the man who took back the record in the name of all that is clean, and so on.

Still, specifically, how many home runs will the savior hit? A lot — so many it’s hard to imagine.

Rodriguez is on pace to hit 54 home runs this season. A sound principle in baseball is that you can project how what a player will do by just looking at his three most recent seasons. Weigh his most recent season three times, the next most recent season twice, and the next most recent season after that once, average them out, account for aging, and you’ll have a decent estimate of how good he is. In Rodriguez’s case, using that 54 number for this season, it looks like he’ll be good for 45 home runs next season. That of course doesn’t mean he will hit 45, just that he’s as likely to hit more than that as he is to hit less than that, and that if he somehow played the same season a hundred times you’d expect him to hit, on average, 45 bombs.

Extrapolating along these lines, Rodriguez looks like he’ll be a 45-home run man for the next three years, a 42-home run man for the three years after that, and then will decline to a 36-home run level in the three years after that. In other words, if he keeps on playing 159 games a year through age 39, he could well hit another 330 home runs, and thus enter his 40s sitting on 850 home runs.

This isn’t really as preposterous as it sounds. From 22 to 29, Rodriguez hit at least 40 home runs every year but one, and in four of those years he hit at least 47. He won’t be as good a player in his 30s as he was in his 20s — he no longer plays shortstop, his batting average will decline, and he’ll continue to lose speed as he ages. But hitters add power as they age, and there’s no real reason not to expect him to hit 40 home runs a season for years to come.

The real variable is how much he’ll play. Most of the players to whom you can compare Rodriguez — Foxx, Eddie Mathews, Mickey Mantle, Mel Ott, Johnny Bench, and Ken Griffey, Jr., to name a few — entered the majors extremely young and burned out in their 30s, retiring early in many cases because of the pounding they’d taken from an early age at demanding defensive positions. Two years ago, I wrote that the Yankees should consider moving Rodriguez to first base, as a way of helping ensure that he didn’t meet that fate. I underestimated the man; he’s having his best season with the bat, and certainly doesn’t look to have much of the air of Eddie Mathews, who retired at 36, about him.

Given his athleticism and his tremendous durability, there’s not much reason to think Rodriguez won’t play 150 games a year for, say, the next six years, enough time to ice the record. In terms of home run records, though, the thing to note is that he doesn’t have to. Halve those 330 home runs and you still have a 39-year-old Rodriguez sitting on something like 685 home runs with years left in his career. Barring inexplicable collapse or a traumatic injury, he’s going to break Bonds’s record, and he actually does have an outside but legitimate shot at hitting 900.

All of this, incidentally, is why I think Rodriguez will exercise the free agency clause in his contract this winter. Why wouldn’t he? His agent, Scott Boras, who could sell a quart of spoiled milk as the finest camembert, can in good conscience shill Rodriguez as someone with a good 350 home runs left in his bat and a reputation as baseball’s savior to cash in on less than 10 years from now. Anyone who wouldn’t want to find out what that’s really worth would be a fool.

tmarchman@nysun.com