After shooting a 74 in the first round, Tiger Woods rallied to card a 68 on Friday and make the cut. He is six shots off the lead. (Andy Lyons/GETTY IMAGES)

Fridays at PGA Tour events once were nerve-wracking for much of the rest of the field, the grinders, and merely a step in the process for Tiger Woods. But put together an uneven game and TPC Sawgrass’s Stadium Course, as irascible a host as the tour knows, and anxiety and uncertainty can pop up in equal measures, regardless of the player.

Woods’s 68 in Friday’s second round of the Players Championship assured only this much: He will play the weekend, something that seemed iffy as he approached the turn Friday, around which he made four straight birdies. But what awaits once he and 71 other players rise on Saturday morning is impossible to tell, because this course and this tournament provide no blueprint to follow, no measurable pattern that might offer a way to forecast what will happen next.

“You just can’t fake it around this golf course,” Woods said.

Woods’s bounce-back performance Friday, which left him 2-under par and six off the lead, doesn’t mean that he, or anyone else, has solved this place with any degree of consistency. Yes, Zach Johnson shot 66 Friday, Kevin Na 69, and Matt Kuchar 68, and they share the lead at 8-under 136. But among some of the field’s most notable names, there was more chaos than calm.

Consider that Rory McIlroy, the No. 1 player in the world and reigning U.S. Open champ, shot 76 Friday and missed the cut by four shots. Steve Stricker, who had the PGA Tour’s longest string of consecutive cuts made at 49, backed up his opening 76 with a 74, and the streak ended. Ian Poulter, who shared the lead after his first-round 65, opened with two double bogeys in his first four holes en route to 76. Martin Laird, who was tied with Poulter overnight, had the lead all to himself before dunking two balls in the water and finishing bogey-double bogey-bogey.

How to figure this place out?

“Hopefully I’m coming back here for another 20 years,” McIlroy said. “If I don’t figure it out on my 20th go, there’s something wrong.”

There might not be anything wrong, technically, with Sawgrass. “It’s very well done,” Phil Mickelson said before the tournament began. But there is little consistency to the champions it has produced. Players of great accomplishment (Woods, Mickelson) and great ability (Sergio Garcia, Adam Scott) have won here. But so have the odd Tim Clark, the random Fred Funk, the surprising Craig Perks and Stephen Ames. Over the past 19 years, 19 men have taken the Players’ title. There are, the saying goes, different horses for different courses. But what kind of horse is suited to the Stadium Course?

“I don’t know what it is about this place,” a beffudled McIlroy said afterward, in the midst of explaining that there is no other course on which he is so uncomfortable.

Consider Woods, who won less than two months ago at Bay Hill in Orlando, the seventh time he has taken that tournament. He has won that many times at Firestone Country Club in Akron as well. Woods has four Masters titles, Mickelson three. Take a course, match a player, and there should be some connection between game and results.

Yet here?

“For the caliber of player they are,” McIlroy said of Woods and Mickelson, “they definitely have got more layouts that are more to their liking.”

For decades, no one has annually found the Stadium Course to his liking. Since 1982, when the Players first moved to this PGA Tour-owned site — where the tour itself is headquartered — only four men have won the event twice: Fred Couples, Steve Elkington, Davis Love III and Hal Sutton.

If the current leader board holds, that number will remain the same. And the list of champions doesn’t figure to include McIlroy anytime soon. He birdied the first hole he played Friday, the 10th, and didn’t make another birdie all day. He had not missed a cut in 53 weeks. This comes not even a week after he lost to Rickie Fowler in a three-way playoff in Charlotte, where he played splendid golf. He was asked whether he hit the ball much differently in his 36 holes here.

“Not at all,” he said. “It’s unbelievable. I shoot 14 under last week and I feel like I hit it just the same this week, and I’m going home.”

McIlroy has played here three times, and missed the cut all three. He skipped the event last year, a decision he regretted. He promised Friday that, despite results, he’ll be back in 2013.

“I’ve come back here a much better player, I feel,” McIlroy said. “A much more consistent player, experienced player, and I felt like I would come here and think my way around the golf course and just try and play steady golf. I tried to do that, and just didn’t happen.”

That would leave Johnson, the 2007 Masters champ. “I feel like the golf course is good for my game,” he said, a nod to the eight birdies he made Friday. It leaves Na, the notoriously slow player who tied for 12th at last month’s Masters. And Kuchar, the permanently smiling three-time tour winner, who has never taken a title of this magnitude.

“This course can bite you pretty quickly,” Kuchar said.

It bit its share of the world’s elite Thursday and Friday. “It’s an absolute challenge,” Woods said — a challenge that, from year to year and day to day, is impossible to tell who will master.