The Post Sports Live crew debates whether the Nationals should make a move to add a missing piece or stand pat before the July 31 trade deadline. (Post Sports Live/The Washington Post)

The Post Sports Live crew debates whether the Nationals should make a move to add a missing piece or stand pat before the July 31 trade deadline. (Post Sports Live/The Washington Post)

If a bat doesn’t feel right to Washington Nationals outfielder Bryce Harper, he’ll toss it right away. Harper can just tell it’s all wrong.

He likes ash wood bats in the winter. Maple wood bats are for the summer. Maples are harder, and that feels right.

Harper, like most baseball players, relies on instinct rather than science when it comes to his preference in the wood used to make his bats. He’s picky because a bat is more than just a piece of wood; it’s an extension of the hitter, moving when he does in hopes of launching a ball somewhere someone can’t get to it.

When it comes to wood preference for their bats, players know what they like and don’t like. Some swear by one type of wood. Others use multiple kinds. Their explanations for why maple is better than ash, or yellow birch is better than maple, or whatever their preferences, are rooted in perception, researchers said. In the case of wood, perception isn’t reality.

Perception

When catcher Jose Lobaton was in Class AAA, someone told him he should use a yellow birch bat because it hardens with each impact. After Lobaton joined the Nationals, fellow catchers Wilson Ramos and Sandy Leon convinced Lobaton to try a maple bat.

When the Nationals signed Jayson Werth for seven years and a $126 million in 2010, the move was largely criticized. The Post Sports Live crew reassesses the outfielder's huge contract and whether the move was worth it. (Post Sports Live/The Washington Post)

“I use both now,” Lobaton said. “Sometimes I’ll pick up a birch, then get a base hit. At the next at-bat, I’ll use the same one. And if I don’t get a base hit, then I’ll use the other one.”

Maple is the wood of choice for the Nationals. Last season, about 70 percent of Major League Baseball players used maple bats, with 25 percent using ash and 5 percent yellow birch, according to MLB Players Association spokesman Greg Bouris.

Fifteen years ago, nearly everyone used ash.

“I think originally when maple came out, guys tried it because it was something new,” first baseman Adam LaRoche said. “Ash was all we’d ever had. Then maple came out and the thought was that it was a lot harder. Ash has the little grains through the middle of it, and over time, those kind of bury into the wood and make the ash harder, but it takes a while of hitting balls on that spot. Maple was just hard right out of the box, and there wasn’t really a breaking-in process.”

Several Nationals said their preference was maple because it’s the harder wood. Nationals hitting coach Rick Schu said that’s why the ball will go farther off a maple bat. Yellow birch is rising in popularity because it’s also a hard wood.

Ash is softer and tends to flake after repeated use, so players prefer maple’s durability. Maple breaks less often than ash, but it also breaks more violently, prompting MLB to add regulations for the slope of grain in maple bats.

Some players, like Harper and shortstop Ian Desmond , are so careful with their bats that they keep them in a temperature-controlled humidor, a practice popularized by the Yankees’ Ichiro Suzuki.

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“There are a lot of guys that can just look at the bat — they can roll it on the ground and put it through their little test to tell if it’s good wood,” outfielder Denard Span said. “I’m not that good with bats. I have a model that I like, and I just get that.”

Reality

Schu was playing Class AAA ball in Ottawa when he first encountered a maple bat. Players tried the bats out in batting practice, and Schu found them too heavy.

Sam Holman, the founder of the maple bat company Sam Bat, was the first to introduce maple bats to professional baseball. He eventually patterned his maple bats to be lighter with smaller barrels. Then former Giants star Barry Bonds started using a Sam Bat and maple’s popularity exploded.

After Bonds used a maple bat to break the single-season record for home runs in 2001, the perception that the harder surface made the ball go farther after impact was difficult to break.

“If Barry Bonds had not been swinging maple when he broke that record, I don’t think anybody would even be talking about maple right now,” said Lloyd V. Smith, a professor at Washington State’s School of Mechanical and Materials Engineering. “There is no magic about maple hitting the ball further. We’ve tested all kinds of wood bats — bamboo bats, beechwood, ash and maple — and wood is wood when it comes to hitting performance.”

Schu’s initial hesitation with maple was right: It’s a denser wood than ash. Even though maple bats can be ordered in lighter weights, they’ll still be heavier than their ash bat equivalents. Smith said a heavier bat increases the hit-ball speed, but it also slows the swing speed, which results in a lower ball speed.

The competition between the two factors leads to virtually no difference between woods. Certain weights and profiles of a bat suit some hitters better than others.

Smith used iconic slugger Babe Ruth as an example. Ruth’s bat was extraordinarily heavy — 40 ounces, Smith estimated — and because Ruth had the strength to control the bat, he had success with it.

“If you’re big and strong and you’re going for the long ball, then you want to get the heaviest bat you possibly can,” Smith said. “On the other hand, if you’re not putting it over the fence because you’re not that kind of hitter, then what you’re trying to do is placement and getting the ball in the hole, and then you don’t want a heavy bat. You want to be getting as light a bat as you can because then at that light weight, you’ll be able to control it better.”

Aggressive drying techniques are often used on maple bats to rid them of any moisture that would make them heavier. A biography of former Red Sox outfielder Ted Williams said he used to put his bats in an industrial clothes dryer in an effort to dry them out. But drying can make maple bats more brittle and leads to breaks.

Smith and physicist Alan Nathan said ash wood is a better choice on average, but both agreed that the type of wood does not affect how the ball comes off the bat. It only affects perception.

“It’s kind of a confidence thing,” Schu said. “Anything that’s going to give you a little bit of an edge mentally, if you think it’s going to help you, then it works.”