One of the reasons I never became a world-class physicist (besides all that pesky Math crap) was the fact that I could never quite wrap my head around the concept of "potential energy." So wait, this thing might possibly have energy inside of it? Potential to do work? What work? Why do these equations have Greek letters in them? And how do you pronounce "Joule" - is it "jewel", like in "family jewels", or "Joel", like in "Billy Joel"?
Anyway, the point of that story is that I'm a moron - I have very little concept of potential, be it in the physics classroom or on the baseball diamond.
Take Eduardo Nunez...please. -rim shot- Like many Yankee fans, I've held out hope that Nunez could turn into at least a passable Major League shortstop. I clutch each of those rare 3-for-4 games and helmet-dropping doubles close to my heart: look at what he can do! He has potential! He only needs to find consistency!
Let's take a look at what my faith has bought: according to Baseball Reference, Nunez has been by far the least valuable Yankee position player, clocking in at an abysmal -1.6 WAR. Even my favorite whipping boy, Chris Stewart, has managed a positive WAR this season (0.5). And yet, if I found myself in a room with Nunez, Stewart and two pink slips, I would still fire Chris Stewart twice.
That these players' actual values fall nowhere in line with their perceived values is due in large part to each player's unique baseball skill set. The legendary Five Baseball Tools are power, batting eye, glove, throwing arm and speed - and in that case, both Stewart and Nunez are true one-tool players.
Neither player can hit - in fact, their batting lines are remarkably similar:
Stewart: .222/.299/.282, 63 OPS+
Nunez: .229/.289/.326, 70 OPS+
But Stewart, as much as I make fun of him, is a quality defensive catcher. He's not the revolutionary uber-backstop the Yankees like to pretend he is, but he grades out well in most defensive metrics. That is his one tool.
Nunez cannot defend his position. At all. He actually grades out far worse with the glove (-1.5 dWAR) than he does with the bat (0.3 oWAR). His tool is his impressive speed.
Taking their ages out of consideration for a moment - Nunez is younger, but at 26 years old, he should be on the verge of his baseball prime - what we have here is a player who can catch versus player who can run. Our rational baseball minds tell us the defensive skill is far more valuable, but there's just something about watching Nunez run, isn't there? He looks like a young colt on the base paths, so raw and powerful and full of...potential. As the old baseball saying goes: you can't teach speed.
The implication has always been that a player with speed and/or power is more valuable, since the hitting and fielding can be taught. And that's true, but only to a very limited extent. As much as we'd like to believe the Yankees can mold the speedy Nunez into an infield version of Brett Gardner, that is simply not realistic. Gardner has an innate sense of the strike zone and natural defensive instincts that Nunez simply does not possess. And at 26 years old, in his ninth professional season in America, Nunez is most likely past the point where he could be expected to develop these skills.
As much as it pains me to admit it, Eduardo Nunez is further below average than any player in the Yankees regular lineup, and that fact is unlikely to change anytime soon. But it's still a joy to watch him run.