It's not like Mark McGwire is hard to figure out. I mean that in the nicest way. The inner workings of this very public figure play out on his face. If you watch him, you know where he is and what he's thinking. And for too long now, he has been in discouraging places thinking tough thoughts.

	Opposing catchers have watched Mark McGwire go yard 583 times.

For most of the 2001 season, McGwire battled a knee injury that did not respond as expected. McGwire was not the player he had been or wanted to be. His confidence was gone. It was never more evident than in the postseason. You could see it on his face.

Against the Diamondbacks in the National League Division Series, he was simply not Mark McGwire. Everyone knew it. And in what would have been his final at-bat, Tony La Russa sent up Kerry Robinson (career: 190 at-bats, one home run, 15 RBI) to hit for him. I'm betting that was a tough blow simply because it was the right move for the Cardinals.

A key to understanding McGwire is understanding what is good for the Cardinals. St. Louis has a good team, so McGwire is potentially walking away from some postseason action in the next few seasons. But McGwire would not hang on for that reason. He would stay on if he could be a leader on that team. Despite having a legitimate contract offer in his hands, for really good money, he is retiring because he is not the player he once was and doesn't want to hang on as some reduced shell of himself.

Physically, McGwire could probably endure some rigorous rehab and come back to hit well over the .187 he finished with this year and maybe 40 to 50 home runs. I think he could rebuild his knee. I just don't think he wants to go through the mental rehab. He knows how low he is now and he knows what it would take to rouse himself out of it. And he doesn't want to go through it.

So Mark McGwire is leaving baseball. He leaves the game with no single number associated with him. Cal Ripken Jr., Babe Ruth, Ty Cobb and many other baseball players are closely aligned with certain numbers (2,131, 714, .367 are all legendary stats). There are more: 60, 61, 56 and 755.

	Mark McGwire spent 10-plus seasons with the A's before being traded to the Cards in '97.

I mention 60 and 61, by the way, because Ruth and Roger Maris held the single-season home run record for so long that the numbers are ingrained as classic and significant milestones. McGwire's mark of 70 didn't make it through three seasons. And I happen to think that 70 meant a lot to him.

I think he enjoyed the summer of 1998 and the role he played in reviving the game. When it was all over, he became comfortable with the number and its stature and with all he had gone through that season. And the single-season home run mark would have been a pretty great souvenir from that year.

But in 2001, 70 is second place.

And now that he's hurt and can't make a run at 75 or 80, he'll just call it a day.

Remember, this is a guy who skipped a chance to hit 50 home runs, back when that was a huge number, to be present at his son's birth at the end of his rookie year. Big Mac has never been a numbers guy, and now he's retiring just 17 home runs shy of 600. But it would have been nice if he had just one number that could stand for all of his achievements.

He doesn't even have a special claim on his uniform number, 25. It's the same number Barry Bonds wears.

Then again, 30,000,000 is a nice number. That's the number of dollars on the contract McGwire chose not to sign.