CHICAGO -- What was suspected to be more than a bone bruise for Carlos Guillen turned out to be significantly worse. The Tigers infielder underwent microfracture surgery to repair what head athletic trainer Kevin Rand called a lesion on Guillen's left knee.

It's an injury more likely caused over time than by one incident, such as the slide into Guillen's knee from Yankees outfielder Brett Gardner that ended Guillen's season last month. It's a significant enough surgery that it puts at least some question into Guillen's readiness for the start of next season.

The timetable suggests Guillen will not be able to put weight on his leg for 6-8 weeks, and he won't be able to pick up significant physical activity for four months. That would put him on track for light running in January. The timetable to get him back to baseball activity is more likely around 4-5 months, Rand said, which would be right around the early part of Spring Training.

"The time frame [for a return to game action] usually on these things is in and around the six-month mark," Rand said. "Obviously, it kind of puts into question him being ready to begin the season."

With so little case history among baseball players, it's hard to tell. Microfracture surgery is more common in basketball, having been performed on such players as Tracy McGrady and Chris Webber. Success hasn't been guaranteed, but the results have improved as the surgery has become a little more common.

"Microfracture surgery, in and of itself, that makes it obviously a longer time period [for recovery]," Rand said.

Fellow Tiger Clete Thomas had the same surgery this summer.

Dr. Michael Warren, who originally examined Guillen in New York after Gardner's slide, performed the surgery. He specializes in knee and shoulder injuries and serves as the team physician for the NFL's New York Giants.

Like others, he suspected something more than a bruise when Guillen's knee showed little progress after three weeks of rest, usually the maximum time for a bone bruise to heal. At the very least, they wanted to take another look while there was still time for recovery to get him ready for next season.

What they found, obviously, wasn't encouraging. Rand compared the injury to a divot on a golf ball. It wasn't a fracture, but the surgery itself involves a microfracture to try to trigger the healing process. Guillen has had knee problems in the past, including surgery to repair a torn anterior cruciate ligament in his right knee in 1999 and 2004.

Until this summer, the Tigers had avoided Guillen in the infield the past couple of years to avoid wear and tear. However, he said he felt more comfortable playing as an infielder than in left field, mainly because he could keep moving and keep his legs fresh. Second base was his fifth different position since 2007.

What it means for Guillen and the Tigers next season is a lot of uncertainty. Even if Guillen didn't have additional surgery and was ready to start next season, the Tigers appeared prepared to go into 2011 with options. Team president/general manager Dave Dombrowski told WDFN last week, "I feel comfortable going into next year at second base with what we have at this point with [Will] Rhymes and [Scott] Sizemore."

Manager Jim Leyland said Sizemore will get playing time at second base over these final two-plus weeks to the season, starting against left-handed pitchers. It isn't difficult to envision a timeshare at second next season, with Guillen also playing there when he's ready while potentially shifting to other spots on occasion.

Before the Tigers can decide where to play Guillen, however, he has to be able to play. That will be the focus of the offseason.

Valverde remains out with elbow tendinitis

CHICAGO -- Tigers closer Jose Valverde was out of action Saturday, and he most likely will remain so until at least early next week with continued tendinitis around his right elbow. It's the same problem that kept him out of action last week, but it has gone on long enough that the Detroit staff doesn't want to take any chances so close to season's end.

"It's the same exact thing [as last week]," manager Jim Leyland said Saturday morning. "It wasn't quite right, and I'm not going to pitch him until it is."

Leyland said Valverde won't pitch until he says he's fine. That appears to be at least a few days away.

"It's still sore," Valverde said. "I'll take a couple days and see how I feel."

So far, there has been no talk about Valverde being shut down for the final two-plus weeks of the season.

Valverde went more than a week between outings before he returned to pitch a scoreless inning with a walk Wednesday at Texas. He threw just two out of 11 pitches for strikes, but they both went for groundouts. After a four-pitch walk, his inning ended when Gerald Laird threw out David Murphy trying to steal second base.

It marked just the second scoreless performance in Valverde's last six outings, though one of those featured an unearned run over three innings in a victory Sept. 2 over the Twins.

Leyland said Phil Coke will serve as the closer for the time being. He will not be used before the ninth inning in those situations.

Jackson gets better break out of box

CHICAGO -- Tigers manager Jim Leyland has pointed out Austin Jackson's difficulty getting out of the batter's box, but hasn't wanted his rookie leadoff man to try to alter his game to do anything just yet. Jackson, however, has had it on his mind, and it helped him get the first base hit off Edwin Jackson on Friday night.

Austin Jackson beat shortstop Alexei Ramirez's throw to first base by a step to leg out an infield single with two outs in the sixth inning. It was the 28th infield hit of the season for Jackson, tying him for sixth in the American League with Seattle's Chone Figgins, according to STATS. The players ahead of him read like a speed roster: Ichiro Suzuki leads easily with 51, followed by Erick Aybar, Juan Pierre and Elvis Andrus.

Jackson could have more such hits, the thought has gone, with a better break out of the box. But Leyland doesn't want Jackson thinking about that.

"I don't think you learn to do that," Leyland said. "I think your swing is what it is, and I think you do the best you can. He did [get a better jump Friday] for whatever reason, but I don't think that's something you can really practice. I think your swing is your swing. We don't want to start changing your swing to get out of the box when you hit .300."

Part of the reason for his better break on that ball, Jackson said, was because he didn't take a full swing.

"It was one of those things where I knew, right when I was swinging, I was swinging at a bad pitch," Jackson said. "So I really didn't take a full swing. I just kind of made contact and was pretty much out of the box already, because I knew that if I didn't get out of the box, there was a chance I was going to get thrown out at first.

"I think the pitches that are down and away, or down the middle, I just kind of throw my bat at it. Knowing that I'm not going to crush it, I just try to make contact, and then I'm already out of the box before the ball hits the ground, pretty much."

Tigers eliminated from AL Central race

CHICAGO -- The Tigers' success in spoiling what remains of the White Sox postseason hopes ended up doing nothing for their own mathematical playoff chances. They finally ran out of the playoff race on Saturday, when victories from the Twins and Rays officially eliminated Detroit from postseason contention.

It's a fate Detroit effectively knew at least a month ago, when the combination of an injury-depleted lineup and inconsistent pitching sent the club falling out of the division race. With a 9-7 record in September, however, it isn't something to which the Tigers were necessarily resigned.

"I agree with what [White Sox manager] Ozzie [Guillen] was saying: You try to win as many games as you can, no matter what your situation is," Tigers manager Jim Leyland said. "You're not thinking about 2011. You're thinking about finishing out as good as you can, win as many as you can. We have a lot of time to think about 2011."

They've had plenty of time to look at potential pieces for next season, with so many rookies in the lineup. Detroit started four rookies Saturday, and brought in two more as pinch-hitters. The rookies combined for eight of the Tigers' 12 hits and four of their six RBIs, including Scott Sizemore's go-ahead three-run homer as a pinch-hitter.

The Tigers still technically have a chance to move up in the standings. Their back-to-back wins over the White Sox the last two days whittled the gap to five games between second and third place. Detroit has finished second in three of the last four years.