Maple is a very dense wood, which tends to make it one of the best species to use for wood bats. Density is directly related to hardness and durability. The denser the wood used to make a bat, the more durable a bat will be and the more pop it will have. Also, maple is a diffuse-porous wood (close-grain). The properties of diffuse-porous wood are such that it will hold together under high intensity impact. Maple will not flake apart on the barrel or splinter. Thus, the more you hit with a maple bat the grains will compact and press together. This makes the bat harder in this area of frequent impact. Maple has the hardest surface of the three major species of wood typically used to manufacture wood bats.
Maple must be dried to a very low moisture content, making it susceptible to gaining moisture over the lifespan of the bat. As the bat gains moisture it gains weight. A maple bat being used in a humid climate will tend to pick up a half ounce to an ounce or possibly more, depending on the climate. Maple is a rigid, sturdy wood and tends to be less forgiving than ash and birch when striking the baseball off the end of the bat or near the trademark.
Before maple bats became popular, most traditional wood bats were made of ash. Ash is more flexible than maple, which many players believe allows them to “whip” the barrel through the hitting zone creating more bat speed. Due to this flexibility ash also, tends to be more forgiving than maple when striking the baseball off the end of the bat or near the trademark.
Ash also needs to be dried to a very low moisture content in order to be used for wood bats. Ash is a ring porous wood (open-grain). The properties of ash are such that the bat will continue to dry out during the life span of the bat. This will cause the grains on ash bats to flake and splinter. Hitting off the face grain (the grain where to logo is placed) will also cause the bat to flake and splinter. Players that are not experienced using wood bats often rotate the bat while hitting, causing them to hit balls of the face grain. This will result in flaking and splintering and cause the bat to be less durable.
Birch is a softer wood which causes it to be more flexible. This flexibility may allow a player to create more whip and generate more bat speed. This softness also tends to make birch more forgiving than maple when striking the baseball off the end of the bat or near the trademark. Like Maple, Birch is also a curly grain wood which lends it to be more durable when making repetitive contact with the baseball in the same area of the bat. In this sense, birch holds together similarly to maple. Birch bats will not flake apart like ash bats.
Birch is softer than many other wood species, causing it to dent slightly when first used. Most birch bats will need to have a “break-in” period in order for the bat to harden as a result of repetitive impact from hitting the baseball. The surface hardness of a new birch bat is not near as hard as a new maple bat which may slightly decrease exit speeds.
Over the course of the last 20 years Maple bats have emerged as the most popular species of wood used by players at the major league level. This is due to the hardness, durability, and overall performance of the wood. Maple bats make up approximately 75% to 80% of all bats used at the major league level. While there are some benefits to ash and birch, most players choose the performance of a maple bat over any other species.