It happens in nearly every game. A hitter swings and not only does the ball come off his bat, so does part of his bat.
Sometimes it’s dangerous, the sheared-off bat hurtling like a misguided spear toward the pitcher, an infielder or even fans in the stands.

That’s been MLB’s goal since 2008, when bat breakages reached an all-time high, with approximately one per game.
Over the past four seasons, MLB has made a concerted effort to make bats safer through specific programs and regulations. In the process, there has been a steady decline in broken bats.

Constant for the past year, breakages currently occur at a rate of around a half-bat per game. Last season, the rate was .50 multipiece failures per game. The most up-to-date breakage information for this season shows a rate of .53 bats per game.

That doesn’t mean seeing such breakages is easy for him, especially if the bats jeopardize someone’s safety.

To have an appropriate slope of grain — or comparison between the grain of the wood and a straight line up the bat — MLB and the Players Association have agreed that a bat’s slope of grain for the handle and tapered regions must be no greater than three degrees, and it must be maintained on the edge and face of the grain surfaces. Also, a bat’s entire grain, including the areas that are stained, must be sufficiently discernible to permit visual grading for the detection of defects.

Such regulations are especially important for maple bats, on which more slope creates a breaking point along which a large, sharp shard can result. Ash bats, on the other hand, usually sustain rupture breaks.

Excerpt taken from;

By Quinn Roberts / MLB.com