The Really Good Ones Have Prehensile Tongues and Arms That Turn Into Guns

Someone explain to me, in terms of baseball, what this means? Please?

And finally, a scout who recently saw Rangers center fielder Josh Hamilton was reminded of a phrase he learned from an old scout: "The good ones have antlers." Said the younger scout of Hamilton: "This guy has a head full."

I'm not even angry. I'm just curious. Could Josh Hamilton be an early product of this research?