traveling at 90 m.p.h. or more you must have better than 20 -20 vision in fact the team eye docs will give you contacts so your eyesight is adjusted to 20 -15.Many players want to use laser surgury ,but this often develops coning or halos which may knock you right out of the big leaques. the absolute best vision is 20-8. So teams are using every edge to try to put the best sighted players on the field.Of course eyesight is only a piece of the puzzle you must also have tremendous eye hand coordination and have good strength. No wonder why hitting a ball is the hardest thing to do in any sport. Interestingly this whole process of hitting a 90 m.p.h. takes less than a half of a second. On top of that you must decide to swing or not to swing in .043 seconds.