"Maple and ash tend to break in different ways. While ash tends to crack and flake off in smaller chunks, maple tends to fracture in bigger, jagged shards."
"Cracks form in both types of wood as a bat is used to hit ball after ball after ball. But the same pore structure that makes ash prone to flaking also channels cracks along the length of the bat, meaning the crack has a long way to grow before it can break the bat in two. And batters tend to notice the cracks or decide the bat has too much flaking and switch to a new bat before the old bat completely breaks.
Because of maple's diffuse pores, cracks in the wood can grow in any direction, making it easier for them to grow out toward the edge of the barrel, causing a large chunk of it to break off entirely. And since maple doesn't flake, serving as a warning to a player that his bat is cracking, "you're perhaps more likely to have bat particles flying through the infield," Smith said."
There are more Maple bats being used now than ever it seems. Barrels are flying across the infield in nearly every game. The maple bats seem to explode on contact, much like the synergy sticks in hockey. I wonder how long before they're banned.