We’re getting close to being able to quantify everything we could ask to quantify on a big-league field. We know about as much about discrete, outcome-level performance as is possible, and we’re learning new things about process and the real physical, physiological, and psychological inner machinery of the game every day. We’re awash with good information.

However, there remain a few aspects of players (particularly at a scouting level) about which we still know relatively little, at least in a direct, measurable sense. This is the first of three pieces (I think it’ll be three; we’ll see) on those not-so-little things we still only know insofar as we can guess them or find someone in the know to tell us. Today, I want to talk about vision.

In one way, it makes sense that we don’t know every big-league player’s precise visual acuity, or scores on proprietary neurological testing games, or performance on high-level tests of peripheral vision. It even makes me happy. Players deserve as much privacy as they can carve out for themselves in this world that demands more of them all the time. Still, it’s a glaring hole in our knowledge base. A baseball player’s vision is as important a datum as a basketball player’s wingspan, but I know of no serious effort to collect or catalog objective information on players’ vision for public consumption.

When people talk about players’ eyes, it tends to be in the context of plate discipline. We all know, of course, that plate discipline requires more than excellent vision, but it does seem to be a building block. Great vision might allow one to pick up the spin axis of the ball sooner out of the pitcher’s hand, or to recognize a smaller difference in release point than a normal human could detect. While Greg Maddux notably doubted it, a hitter with great vision might even be able to discern a difference in pitch speed a hair sooner than other guys.

Perhaps just as obviously, but talked about in these terms less often, batters with better vision are probably better able to make contact (and especially good contact) consistently. One of my favorite nuggets (I’ve written around it before) concerns Brian Harper. A catcher in the big leagues from 1979-1995, Harper once participated in a study of hitters’ ball-tracking ability.

Quick numbers:

  • For a normally positioned batter, it would require eye movements at an angular velocity of about 500 degrees per second to actually watch a fastball from the moment it leaves a pitcher’s hand to the moment it crosses home plate.
  • Normal human ability tops out in the 70-75 degrees per second range.
  • Harper (partially, we must note, because he used some slight head movements the researchers believed would make actually hitting the ball more difficult) had easily the highest angular velocity in the pool of players studied, around 120 degrees per second. He was better able to track the flight of an oncoming pitch than any other subject.

People who remember Harper will remember that he didn’t walk at all, so his exceptional vision didn’t beget plate discipline. What it did allow him to do, in the words of Bill James, was to “hit .300 in his sleep,” and to make contact basically all the time. Harper struck out in 5.6 percent of his 3,386 career plate appearances. He was a slow-footed right-handed hitter without power, yet his career BABIP was .295. Two of Harper’s sons became minor-league hitters. He’s been either managing or serving as a hitting coach in the minors for most of the time since he retired, and seems to have a knack for boosting the profiles of hitters like him.

Harper was also worth a bit more than 20 runs as a framer, during the portion of his career for which we have enough data to even estimate framing skills (the lion’s share, because he bloomed so late). That provides a segue to other interesting areas in which great vision might help a player, in ways we intuit but might not fully appreciate. A catcher who can see and assess a pitch out of the pitcher’s hand has an incrementally better chance of anticipating where it will be and what trajectory it will be tracing when it reaches his glove, and so can probably catch it more quietly and present it better to the umpire.

Pitchers can benefit from great vision, as can fielders all over the diamond when they make throws. The interaction between the eyes and the body when throwing toward any particular target is often taken for granted, and no one reaches the majors without being able to do it all without thinking, but that doesn’t mean that exceptional vision can’t permit unusual accuracy on long throws and on short ones. (Willie Mays credited his vision for the accuracy of his great arm.)

Most interesting to me, though, is the possibility that great vision makes great outfielders. Our reams of new information about baseball tell us that, with apologies to Jim Edmonds and Andruw Jones, playing deeper is better. The tradeoff of allowing a few singles (and not even all that many, because we know with considerable certainty now that fielders are almost universally better coming in on flies than going back on them) is well worth preventing a few extra-base hits. Yet, some players don’t feel comfortable playing as deep as they might optimally be positioned. That can be about arm strength, especially in the case of injuries (Bryce Harper’s in 2016 has been documented), but maybe it can also be about seeing the ball off the bat.

Consider the outgoing and incoming Cubs center fielders, for instance. Dexter Fowler is fast and has great body control. When the Cubs asked him to play deeper last season he did, and he was a better center fielder than he’d ever been before. Still, Fowler has always seemed slightly tentative in the field. He takes conservative angles on anything hit up the gap. He got the wrong break more often last season than in 2015, though he was better able to recover when he did and the mistakes were less costly when he couldn’t recover. Fowler doesn’t seem disinterested or timid; he just seems not to have terrific confidence in his reads on fly balls.

Albert Almora is less athletic than Fowler. He’s smaller and he’s slower. Yet, he’s a much, much better center fielder. Some scouts swear that he’s a 70-grade center fielder, despite 40-grade speed. That’s extraordinarily hard to do. Almora gets great jumps, runs at full speed to the spot where he anticipates encountering the ball, and often comes up with it. That peculiar competency could come from reps, from Almora’s hard work taking fly balls and learning how they look off the bat. On the other hand, Fowler works plenty hard in his own right, and has more experience than Almora. The much more likely explanation is that Almora has some intrinsic, physiological advantage over Fowler as a tracker of fly balls. The most likely source of such an edge is vision.

If you’ve been nodding along and waiting for the point, I have to stop here and apologize. Little of this is new or insightful. I just thought it made sense, as we await another season and dig into new data sets that help us understand the way MLB-caliber players play baseball, to make note of a vital statistic we can’t find on their pages at Baseball Reference, Baseball Prospectus, Perfect Game, Baseball Savant, or anywhere else. Unless we steal Jeff Luhnow’s password. You don’t suppose he forgot to change it, do you?

Thank you for reading

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Banknotes Harper!
What about the role of the dominant eye in hitting? I have read that hitters are more comfortable with the dominant eye closest to the pitcher (I don't remember exactly where, but I believed it was Will Carroll on BP). Most people's dominant eye is opposite of their handedness, but not all.
Your statement about eye dominance is not the case. Approximately two-thirds of the population is right eye dominant. When it comes to hand dominance it is estimated that between 88-92% of the world's population is right handed. Also, some studies have not shown any advantage to the hitter if his dominant eye is closer to the pitcher.
I know of no serious effort to collect or catalog objective information on players’ vision for public consumption

Well I seem to remember an article on this site that provided evidence that Mark Reynolds is blind. Are you saying that wasn't serious?

And of course the research on umpire vision is widely known by every heavy drinker in the stands.