Now, Lester avoids throwing to any base, which was evident during Game 1 of the World Series.

Besides being known as one of the best pitchers in baseball, Cubs ace Jon Lester is known for his inability to throw to first base. He has a history of making horrible errors when making pick-off attempts or simple throws to first after fielding the ball.

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Besides being known as one of the best pitchers in baseball, Cubs ace Jon Lester is known for his inability to throw to first base. He has a history of making horrible errors when making pick-off attempts or simple throws to first after fielding the ball.

Now, Lester avoids throwing to any base, which was evident during Game 1 of the World Series.

In the third inning, Indians shortstop Francisco Lindor took a large lead off first base and broke toward second as Lester stepped off the rubber in what appeared to be a pickoff attempt. If Lester had thrown to first, Lindor would be a guaranteed out.

But Lester just stared at Lindor and refused to throw to first base. He cannot confidently make this seemingly simple throw.

How is it possible that one of the best pitchers in baseball is unable to perform this basic skill? The throw doesn't even need to be incredibly accurate—just in the general vicinity of his teammate.

It all comes down to a phenomenon called "the yips."

The yips refers to a mental state in which a basic athletic skill becomes virtually impossible to perform. For example, a golfer suddenly can't sink a three-foot putt or a football kicker suddenly can't make a field goal—a situation that Patriots kicker Stephen Gostkowski appears to be dealing with.

The first inclination is to say it's a psychological issue. But according to Dr. Rob Bell, a sport psychologist who specializes in helping athletes conquer the yips, the explanation is a bit more complicated than that.

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"The debate is whether this is a physical issue or a mental issue. It's really a neurological issue," Dr. Bell says. "We have these movement patterns we've been doing our whole lives. What happens is there is an incident that happened that caused a neurological pathway to fray."

For Lester, the "incident" might have been a missed throw to first. For Gostkowski, it might be his missed extra point during the 2016 AFC Championship game.

Athletes make mistakes. It's an inevitable part of playing the game. However, sometimes the memory of the mistake haunts an athlete and causes anxiety that screws up a neurological pathway.

"Too often there's the thought of something we don't want to happen," adds Bell. "'Don't throw it away' pops in the head and that's a killer right there. It's a neurological issue that's exacerbated because of the anxiety that it could happen."

Lester knows exactly how to throw to first, but his body simply won't perform the way he wants it to.

So how do you cure the yips? It's a difficult proposition, as evidenced by Lester's continued struggles. No doubt he's consulted with sport psychologists, but the problem persists.

One options is to change the feel of the skill. This allows an athlete to move on from the faulty pattern and relearn and gain confidence in a new movement. For example, golfers sometimes change the grips on their clubs.

But for Lester, it's more challenging because he can't change the feel of the baseball. He could try changing his throwing motion to first, but that's a risky proposition considering he's spent his entire baseball career throwing a certain way.

According to Bell, the only thing that appears to be effective is imagery and visualization to address anxiety.

"The only thing I've found successful is imagery and visualization," he says. "Have it really specific and guide them through that imagery so they can feel what it's like when they are having success. And what it's like when they don't have that problem."

Still, this is not a surefire way to cure the yips, and athletes who implement these strategies may continue to experience problems. If it happens to you, here are a few tips you can use to battle this debilitating phenomenon.

Gain confidence with the skill during practice and other non-pressure situations.

Before a game, imagine having success with the problematic skill. Think about how you and your body feel when you succeed.

Avoid negative talk or thoughts about what you don't want to happen. Instead, focus your mind on what you want to happen.

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[UPDATE] A recent Sports Illustrated article detailed Lester's struggles with the yips, and explained how he has overcome the issue: To avoid throwing to first at all costs. Here are several of the strategies that Lester and the Cubs employ to limit the chance of a mistake: