Business Insider Science posted a great video titled The Science of Hitting a Major League Fastball, you definitely need to check it out. The basic summary is it is very hard and should be physically impossible.
It reminds me of great scene from the movie A League of Their Own. Dottie Hinson explains she is quitting baseball because it just got too hard. Jimmy Dugan explains it is supposed to be hard. If it wasn't hard everyone would do it. The hard is what makes it great.
I think this video by Business Insider Science sums up exactly what Jimmy Dugan was trying to say.