Chin-lung Hu, an infielder in the New York Mets farm system, had to leave his Triple-A team in Buffalo, N.Y., on June 15 to get treatment at the major league team's complex in Port St. Lucie, Fl. His condition: the yips.

Hu is a promising and accomplished young ballplayer. He hit .474 and knocked four homers and 12 RBIs to power Taiwan to the 2002 World Junior Championship game, and Hu was named the MVP of the 2007 Futures Game. But he can't throw from second base to first anymore. His throws are wild and off target, and for a player whose strength is his defense, this a career-threatening problem. The Mets aren't saying how they plan to treat Hu's condition, but they've put him on the seven-day disabled list.

New York baseball fans are familiar with the yips. The second baseman on the dynastic Yankees teams of the late 1990s, Chuck Knoblauch, was forced to move to left field after the 1999 season when his throwing yips made the Yanks miss several outs at first base. He never got his throwing woes under control.

Washington National Rick Ankiel is famous for being an ex-pitcher who moved to center field and went on to get an on-base-plus slugging percentage of more than .800 two years in a row. He made the switch because the yips killed his pitching career.

Second baseman Steve Sax was the modern player who made the yips famous--so famous that the condition was known as Steve Sax Syndrome for a time. He had 30 errors in 1983 because of his difficulty throwing to first. Sax's tale ends happily; he shook off the yips and by end of his career was considered an excellent fielder.

What are the yips? The Mayo Clinic says the condition can be psychological, neurological, or a combination of both. More specifically, they are muscle spasms caused by performance anxiety or by a neurological dysfunction called focal dystonia. The latter is caused by the over-training of muscle groups that execute a repetitive action. It often afflicts classical musicians. Botox injections can yield temporary relief but will not cure the condition. Instead, the afflicted must retrain the muscles to establish a rewiring of the part of the brain that controls the pertinent motor movements--the sensorimotor cortex.

The Mayo Clinic recommends that people with the yips first try changing the way they execute the task that is being affected. For example, someone who putts left-handed might try putting right-handed, or try using a different grip on the putter. Even if the cause of one's yips is neurological, pressure and anxiety usually worsen the condition. For this reason, the Mayo Clinic recommends relaxation, visualization or positive thinking, according to the non-profit medical research group's website.

It's like you're on a cliff and you tell yourself not to look down or don't look at that pink elephant in the corner of the room. No one understands until they go through it themselves. That's how catcher Jarrod Saltalamacchia described the yips to ESPN in 2010. Saltalamacchia couldn't throw the baseball back to the pitcher. His throws would end up bouncing off the ground in front of the pitcher, or sailing into center field, or going to the second baseman. The catcher started 82 games for the Texas Rangers in 2009 but lost his job in 2010 because of the yips. He was sent down to the Rangers' Triple-A club in Oklahoma City to work through his problem. While down on the farm team, he batted .339 and called excellent games. He just couldn't return the ball to the pitcher.

Saltalamacchia found help from Tom Hanson, a man who has a Ph.D. in physical education from the University of Virginia but practices what he calls energy psychology. He has a website called YipsBeGone.com. The catcher got rid of his yips by tapping various spots on his body. He does it subtly, so few people notice. Saltalamacchia makes a circuit around his body with his finger.

Tapping helps clear out the negative emotion, Hanson told ESPN. Say you struck out to end the seventh inning, and you still have to play defense and might come up to bat again. How to clear out that negative emotion? You focus on the negative. Start on your eyebrows. Focus on the negative. Each site, your eyes, below your nose, below your lip. The idea is to do a tap lap, go down and around, tap the top of your head, then start again. Tapping helps clear out the negative emotion.

The causes of the yips are complicated, intertwined, and vary from person to person. Treatments vary as widely as the causes. For Saltalamacchia, who is now the starting catcher for the Boston Red Sox, the answer was in a soothing ritual that somehow spoke to his problem. Many afflicted by the condition never find their cure.