Do we now know the reason behind Tiger Woods' up and down tournament at the Masters?

Up and down for Tiger meant 12 birdies and an eagle combined with 11 bogeys, excellent by normal standards around Augusta.

Immediately following the Masters, Tiger underwent arthroscopic knee surgery to repair cartilage damage in his left knee, as we all know.

But what also emerged is that Tiger had been playing in pain since the middle of last year.

Anyone who has had a bad knee knows that the pain doesn't get easier with time - it gets worse.

Most of us spend much of the day upright (hopefully) which means weight is pressing down through the hips to the knees all day long. Throw in walking 72 holes of up and down terrain at Augusta and my guess is Tiger's inability to get going on Saturday and Sunday was because of severe pain in his knee.

I also suspect he didn't take pain killers to avoid making himself drowsy and unable to focus.

The amazing thing is that he still finished in second place. And never said a word about it until he revealed all on his website this week.

But amazing and Tiger Woods are synonymous.

What his knee surgery means is that he misses the next few tournaments while he rehabs and gets ready for the U.S. Open.

Organizers at the Wachovia Open where Tiger would have defended in two weeks say they won't be hurt by his absence because they sold out their tickets several weeks ago - largely because he would be there defending.

But the TPC the following week could be in trouble.

It's just more proof that, as Tiger's health and well-being goes, so goes the industry.