As Tiger Woods joins the PGA Tour for the first time in 2012 at the AT&T National at Pebble Beach this week, the speculation is coming fast and furious about how he will perform this year.

There are plenty of variables to consider, enough to fill a classroom blackboard. There’s the new swing, the new coach, the new caddy, the reconstructed (and destined to be replaced) knee. Usually gazing into a crystal ball is associated with seeing the future clearly; with Woods, it’s more like looking through a kaleidoscope and trying to choose from dozens of possible outcomes.

But the key factor is his mental state. Former Washington Redskins tight end and current broadcaster Rick “Doc” Walker played with and against some of the best players of all time. I asked him if his list of the best players he ever saw and the toughest players that he ever saw had any overlap.

“It’s virtually the same list,” he said. “The best players are almost always the toughest players.”

Walker believes that a tolerance for pain is essential for greatness in that sport. When that tolerance is diminished, you are no longer great.

For golfers, pain is seldom the obstacle that must be overcome. The great equalizer is nervousness, debilitating fear of what might happen. Some players simply hover at a performance level that never really brings them into the withering spotlight of major championship competition. Other golfers can overcome it for a round or two. But the greats thrived in the situations that turned their opponents’ knees to jelly.

There is a limit to how long this emotional cartilage can last. Bobby Jones quit in his prime because he couldn’t stand the nervousness anymore. Ditto Byron Nelson who reportedly said “got tired of throwing up every Saturday night”. Hogan and Snead were reduced from titans to mortals by the nerves that eventually robbed them of the ability to putt. When the ability to handle pressure changes, the golfer changes with it; it just remains to be seen how profound and how persistent the changes will be.

For the better part of 12 years, Woods built an internal castle of strength, resolve and confidence. From the rooftops of this mental fortress he rained down destruction and domination on his peers, amassing a record of success rivaled by only a few hallowed names in the history of the game. And in the 2008 U.S. Open, Woods won an 18-hole playoff while hobbling on a broken leg.  That performance, along with Ben Hogan’s 1950 U.S. Open playoff win with his body still healing from a near fatal car crash, is proof positive that golfers are athletes.

No competition or competitor brought Woods down; ironically, the gates were opened by Tiger himself and the angry mob did not delay in storming the castle. The scathing criticism from the media, sponsors and the public created gaping cracks in Woods’ confidence. We saw Superman exposed to Kryptonite, and to most it was not a pretty sight.

Over the last two years, Woods has pieced his life and his game back together. He seems calmer and more content with being a father rather than an athletic icon. All of these were good and necessary things in the growth of the man. But the mental realignment that came with the public humiliation and private rehabilitation seems to have left a cottage where the castle used to stand. Sure, Tiger has three straight top-3 appearances. The swing that he has adopted under the tutelage of Sean Foley seems to be close to what they were envisioning in terms of ball-striking results. And while Tiger is nowhere near the longest player on the Tour, he and Foley seem to be developing a swing and a strategy that will produce a more controlled game and a controlled result. In fact, even Tiger’s on-course demeanor has been tweaked to limit out of bounds behavior in the same way that the swing has been modified to produce fewer out of bounds drives. But the spectacle of the greatest frontrunner in the history of the game losing to his playing partner on Sunday on multiple occasions gives one pause. The question arises: is Tiger’s current mindset one that makes him more stabile off of the course but less stabile on it? The difference between a mentality that produces Saturday leads and one that produces Sunday winners can be summed up in two names: Greg Norman and Tiger Woods.

All of the adjustments, combined with his legendary work ethic, will likely bring Tiger back to being one of the best players in the world. But if he is going to resume his place as one of the best players that has ever lived, he must have some form of the same fire and ice that got him there the first time. Woods is stepping into a familiar course this week that his been the scene of some of his greatest glory.

But with his game slightly diminished and a generation of young stars that have no institutional fear of him, it is also a brave new world for Tiger in 2012. Woods has never been content with simply competing. His interest lies only in winning, especially on the biggest stages. Starting with Pebble Beach, the world will be looking to see if Tiger is back. If he isn’t, will the world be satisfied with a mere Eldrick? More intriguingly, will he?