In 4797 career at bats, going back to 1986, McGwire has deposited the ball in, off, or over the outfield seats 414 times. That's a homer every 11.58 at bats. The media has made much over the years of Mark's at bats per tater (ABPT) rate, especially the fact that it's Ruthian and beyond.

That's a long track record. But is it his real rate as of June 3, 1998? This season, he has 27 homers in 175 at bats, or an ABPT of 6.48. That's quite a rate jump. So, what's his real rate? Hmmm ... more on that in a minute.

Let's assume for the moment that he's going to continue to knock one out every 11.6 at bats, his career rate. Will he get the record?

Mark has played in 52 games, but his team has played in 55. And, all those walks count as plate appearances, but not at bats, so he's had only 175 at bats, or 3.2 per game.

Despite his well-documented injury history, McGwire has been in the neighborhood of 500 at bats in seven of his eleven full seasons. So, let's assume he stays in the lineup, even with his bad back – to reach this record, he's going to have to play day after day, not sit "day-to-day."

And let's assume he continues to average 3.2 at bats in the remaining 107 games. That makes around 342 more at bats. With an ABPT of 11.6 at bats, he should hit about 30 more homers. Adding this to the 27 that he has currently hit, that works out to 57 for the year.

That doesn't mean 62 is out of reach, even if McGwire's still a 11.6 ABPT guy. Let's roll the die and see if he can get there.

Think of a McGwire at bat as the toss of an 11-sided die with one face painted red, the others painted blue. If the red side comes up, then we give Mark credit for a home run.

This is much less fun than watching gopher balls bounce off Waveland Avenue, but it's how statisticians – actuaries, accountants et al. – think of the world.

If we toss the die 342 times (at bats), then the average number of times that Big Red lands facing up is 29.53. However, it is still possible that it could appear 35 times, to give him the magic number, 62.

We can easily calculate the likelihood of the die coming up red 35 times – that is, the probability of McGwire hitting 35 more. (This next step requires a little bit of math, the central limit theorem. Just keep reading to cut to the chase, or jump to McGwire and the central limit theorem.)

And the answer is: The chances of this occurring are about 16 percent. If McGwire's real rate of homers is 11.6 ABPT, and if he stays healthy, he has a one-in-six shot at reaching 62 homers.


27 + 38

But his rate this year is 6.48 ABPT. Wow. But we have to be careful here, because the fact is that someone who hits homers once per 11.6 at bats will have short periods where he hits them once per six and a half.

When you maintain an ABPT of 6.5 for two months, however, that's pretty significant to a statistician. In fact, we know there is only about a 33 percent chance that someone who normally has 11.6 ABPT would have 6.5 ABPT for two solid months. (Jump to McGwire and ABPT #1 to see how we figure this.)

Any ol' weekend sportscaster can tell you McGwire is hitting a homer every six times up, but what is the rate that a statistician can rely on?

Well, it ain't 11.6, and that's news, statistically speaking. (Jump to McGwire and ABPT #2 to see the math which says that, despite his career rate, McGwire's no longer just an 11.6 ABPT guy.)

Remarkably, McGwire has taken his incredible tater rate to a new level. So what is it? While it's theoretically possible that the new rate is 6.5 ABPT, it's extremely unlikely. Increases in walks, mounting pressure as he gets closer to Maris's record, and nagging injuries make it more likely is that he will continue to slug at about the rate he's maintained since 1991: a homer every 9.07 at bats. 

Given our estimate of 342 at bats the rest of the way, that works out to another 38 dingers. And 27 + 38 = 65.

Congrats, Mark!

But, just for fun, let's play the games anyway.