Are metal bats riskier than wood bats?

People claim that balls come off a metal bat faster and thus make them more dangerous, but it doesn't look like there is a big difference.

Certainly kids have been hurt, and at least 16 have been killed by balls hit with metal bats since 1991, including 18-year-old pitcher Brandon Patch, hit in the head by a line drive during a game in Montana in 2003.

Diegnan says only two kids were killed by wood bats during this same stretch, but considering roughly 90% of young players use metal bats, the ratio doesn't necessarily suggest the composition of the bat is to blame.