I would like to hear some facts on the effect that a baseball player's eyesight has on his batting ability. It's one of those areas of baseball where I am not too familiar with the details. Sometimes I hear it mentioned in relation to historically great hitters ("he had quick wrists, an excellent feel for the strike zone, and perfect vision", whatever), and I've also heard poor eyesight as a cause of a batter not being able to fulfill his potential. It's also an issue that is often reference in the steroid debate. But I've never really heard this explored in much depth, and I'm curious.
To be clear: I'm not referring to a "good eye", but the actual quality of eyesight.
This is something that seems so obvious -- good eyesight is obviously going to help anyone have a better chance of making contact with a ball flying toward him at 90 miles an hour. But perfect vision seems like such a rare thing among adults, and contact lenses obviously put everyone at a more equal playing field than was possible several decades ago. So how much difference does it really make these days? Is it something that's tracked in baseball players, particularly at the minor league level? Are there examples out there of players whose good eyesight has made a significant difference in their hitting ability, or of players whose poor eyesight significantly hampered them?