I am a big believer when it comes to martial arts as a training technique in baseball.
Many years ago we hired a Karate instructor to work with our college baseball team during the winter. He knew nothing about baseball and I knew nothing about Karate. After several meetings we took the Karate drills that related to baseball and put together a program. Our players would go through one hour of Karate 4 days each week.
The results were amazing, increased flexibility, better balance, better conditioning, better mentality, better body control, and quicker reactions. We worked with this instructor for three years. A combination of luck and this training resulted in absolutely no injuries serious enough for any player to miss a game in three years.
To this day, our former players still talk about those old Karate sessions. I don't know of anything I have ever seen that produced so much improvement away from the baseball field. There really is no danger involving the mind, in fact, it actually helped in controlling the mind and using the mind.
None of this was easy at the beginning, but after time players could do things they never imagined. One day the instructor came in and laid face down on the floor with his arms reached straight out above his head. He then took his finger tips only and proceeded to do push ups. This looked completely impossible. By the time the season started most of our players could do it. Our pregame stretching would end with players doing these push ups. We just did it to blow everyone's mind. I didn't do it, but it involved using muscles in the body rather than the arms.
Once again, we designed a program that used certain Karate techniques and movements that were related to baseball. We weren't breaking boards or bricks. I'm positive that it improved every player in one way or another.