It should have been the simplest thing, really. Something Eno Guerrero had done almost every day for the previous 20 years. All he had to do was lob a baseball over the plate and let the batter hit it. But he had never lobbed baseballs like this before, with the stands full, former president George H.W. Bush leaning against the screen and this nagging sense that a television lens was searing into his back.

He stood on the mound and he felt very much alone.

Everybody was waiting, watching to see Guerrero, batting-practice pitcher to the Red Sox stars, get taken deep in last year's Home Run Derby by David Ortiz.

If only he could throw a strike.

His first pitch was too high. His second too low. And suddenly the worst thing happened. The fans began to boo poor Eno Guerrero.

"It's different," Guerrero said one recent day as he rested in the Red Sox clubhouse after throwing an early batting practice at Oriole Park at Camden Yards. "You don't have a batting cage. It's just you and the batter and the catcher. You don't look around, you just have to throw the ball. It takes you a couple of pitches."

Eventually he was able to recover enough that Ortiz managed to hit a handful of home runs, falling well short of winning the tournament but leaving everybody gasping with a shot that hit the roof of the stadium. It was a respectable performance, but Guerrero had been brought to Houston's Minute Maid Park to help Ortiz win the contest. And in that regard he had failed.

On Monday night they will begin another Home Run Derby, with sluggers from all over the world taking shots at Comerica Park's distant blue fences. But no matter how hard they swing, they will only be as good as the ball that bloops toward them. Their fate is tied to the most anonymous people in the stadium.

Or, as Mike Piazza said, "If you have a pitcher throwing the ball over the plate, then you will do well."

Which is not as simple as one would think. For there is a science to throwing pitches that are meant to be hit over the fence. And the men who do it well are surprisingly in demand. Such as Ben Strack, a high school teammate of Diamondbacks outfielder Shawn Green who found himself introduced to the right people and started throwing to hitters in home run contests, becoming so proficient at this that players began inviting him every year to throw to them. And each time, it seemed, one of his batters won.

Eventually this proved to be a tedious process. Strack found himself destined to bigger things, moving on to graduate school and eventually earning a Ph.D. He now works as a sports psychologist in Southern California.

Orlando Gomez is not a doctor, but the Orioles' batting-practice pitcher is known to be one of the best at his job in the majors. He was the Mariners' hitting coach for the last two years, earning such affection from Ichiro Suzuki that Ichiro said he would only consider representing Japan in Monday's contest if Gomez was his pitcher. Gomez has endeared himself to his new club, throwing primarily to a daily hitting group of Miguel Tejada, Sammy Sosa and Rafael Palmeiro. Tejada, in fact, had already promised Gomez that he would take him to this year's home run contest, until the event's rules were changed to allow only one player from eight geographical locations to participate. Tejada, who won last summer's event, was usurped by fellow Dominican Ortiz, meaning Gomez will spend these days on vacation with his wife.

"You have to maintain your velocity," Gomez said when asked what makes a successful batting-practice pitcher. "Most of the time you are trying to keep it straight. You start throwing sinkers and cutters and the hitters are going to get angry. You have to find your release point and stick to it."

Gomez, a career minor league catcher, found himself as a big league batting-practice pitcher when he wound up working with the Cleveland Indians in the 1980s and hitting coach Bobby Bonds marveled at his ability to throw pitches in exactly the same place.

"You're the human pitching machine," Bonds declared. The reputation stuck.

Gomez has noticed that he's not the only catcher to thrive as a batting-practice pitcher. Guerrero was also a catcher, as was former Royals Manager Tony Pena, who threw to Tejada at last year's derby. Dave Valle, who has also pitched to a winning home run contestant, is a former catcher, too.

"Maybe it's because we have to make those accurate throws to second base," Gomez said.

Guerrero isn't so sure. He bent his right arm into an L and began to imitate a throwing motion. Because catchers have to snap quick throws back to the pitchers using only their wrists and forearms, they develop a skill for firing the 50-foot pitches that all good batting-practice pitchers need, he said.

It's an acquired talent.

And those who are good at it can live quite a life. Last year Guerrero flew to the All-Star Game on a private jet with Red Sox outfielder Manny Ramirez and his family. He spent the week as the guest of Ramirez and Ortiz, riding and dining with them and sleeping in their plush hotel. He got his own locker in the big clubhouse and his own all-star jersey. Then Muhammad Ali walked into the room. Guerrero was thrilled. Muhammad Ali! He shook the champ's hand and then had someone take their picture.

Suddenly the booing didn't seem so bad.

Who knew lobbing home run pitches could take you so many places?

In tonight's derby, David Ortiz will take lobs from Eno Guerrero, the Red Sox' batting-practice pitcher considered an ace at throwing a home run offering.