Can clay cure John Isner's woes?

The past 10 months have been memorable for John Isner, although not necessarily in the way he wanted. Sure, Isner made headlines around the world for outlasting Nicolas Mahut 70-68 in the fifth set at Wimbledon in a match spread over three days, reminiscent of a cricket Test without the tea. And Isner finished the season in the top 20, a significant first.

But the 6-foot-9 native of Greensboro, N.C. -- a gentle giant if ever there was one -- has struggled with his health since the epic, and record, tilt in southwest London, contributing to a slide in the rankings and loss of belief that's only now being reversed.

"It's been frustrating for sure," Isner said in a phone interview on his way to practice. "I thought, going into this year, my results would be better than they are now. I lost a handful of tough matches that kind of took my confidence out of me a little. It hasn't clicked like it did last year."

There were few signs of what was to come in the immediate aftermath of Wimbledon, a time when Isner stood squarely in the spotlight, which included appearances on the "Late Show With David Letterman" and other talk shows. In Isner's first tournament back, he reached the final in Atlanta, but was edged by the new U.S. No. 1, Mardy Fish, in a third-set tiebreaker.

Drained from playing in the intense heat in Atlanta and still recovering emotionally and physically from Wimbledon, Isner was forced to withdraw from the Canadian Masters. A week later, upon returning at the Cincinnati Masters, he rolled his right ankle.

Isner refused to bail from the impending U.S. Open, where he'd upset Roddick in a defining win a year earlier, even though his ankle was nowhere near 100 percent. Not surprisingly, he was ousted in the third round by eventual semifinalist Mikhail Youzhny.

Isner says the ankle "still feels a little weird." However, he's free of any pain.

"Basically my offseason training with him was an hour and 15 minutes because we thought he had a stress fracture," said Isner's coach, Craig Boynton. "It wasn't. But if it hasn't been one thing, it's been another."

Instead of preparing for 2011 and the Australian summer, a pivotal block, Isner practiced only once.

But after a tuneup tournament in New Zealand, he decided to give the Australian Open a shot. However, Isner was on the wrong end of a marathon this time, ousted in the fifth set 9-7 by Marin Cilic in the third round.

More woe followed.

Isner failed to convert four match points against dangerous, albeit flaky, Russian Teymuraz Gabashvili in Delray Beach; blew a two-set lead to Chilean journeyman Paul Capdeville in the Davis Cup; fell flat against Roddick in Indian Wells; lost to one of his college rivals, Kevin Anderson, in Miami; and saw two match points evaporate versus Ivo Karlovic, at 6-10 the only tour player taller than Isner, in Houston.

His ranking has dipped from a high of No. 18 in July to 29th to a recent stint in the low 30s. An 8-8 record and two quarterfinals at smaller events are all he has to show for 2011.

When asked in March whether he'd like another player's stroke, Roger Federer said he wouldn't mind possessing Isner's mammoth serve. (Last year, Isner became one of five men to surpass 1,000 aces in a season.)

Isner, in turn, would take anything near the 16-time Grand Slam champion's percentage of return games won. Isner rests 75th, one spot ahead of Karlovic, who doesn't move as well from the baseline and has difficulty driving through backhands. Isner has gone a less-than-stellar 4-for-33 on break points in his ATP defeats in 2011.

"When I get a break point, I play it passively and the guy flat-out runs me around and beats me," he said. "That's just not the right way to play. That's the main focus for the rest of the year, and especially this clay-court season -- anytime I get a break point, to go after it. A lot of times I maybe put too much on that. I look at it as, 'Here's a break point, it's essentially a set point with how I can serve.'"

Isner and Boynton have been addressing this issue during the nine days of punishing training on clay in Tampa. Isner goes hard for six hours two days in a row before easing off.

Given his lack of prep in the offseason, Isner labeled the sessions "huge."

"It's all about getting fitter and more comfortable on the clay, a lot of repetition," Isner said. "I haven't really been able to do that much since the end of last year. I feel really, really fit."

Far from dreading red clay -- a surface unkind to American men since the departures of Andre Agassi, Jim Courier and Michael Chang -- Isner departs Friday for Belgrade, where he squandered a match point in a loss to pal Sam Querrey in the 2010 final.

By the time his career is over, Boynton figures clay will be Isner's second-best surface, behind a slow hard court. Allowed time to line up shots, towering pros such as Robin Soderling, Juan Martin del Potro, Ivan Ljubicic and Querrey have all enjoyed success on dirt in recent years.

For now, Boynton suspects a change in fortunes is around the corner.

"I'm starting to see that eye of the tiger again and starting to feel that hunger and desire from John," Boynton said. "We all view Andy as the No. 1 American, but good for Mardy that he's been able to break through that now. Once one can do it, I hope John can take a look at what he's doing and catch him, and look to catch him. I think he's ready for it."

London-based Ravi Ubha covers soccer and tennis for ESPN.com. You can follow him on Twitter.