When Jason Heyward was a 20-year-old rookie in 2010 and homered in his first at-bat on Opening Day and finished the season with an on-base-plus-slugging percentage (OPS) of .849, the baseball world could only imagine the numbers he'd put up throughout his career.
Injuries and some inconsistency have slowed down the Atlanta outfielder a bit with the bat, but there's another wrinkle to Heyward's game that's been excellent over the past several seasons, and so far this season, it's been flat-out elite.
As we approach the end of the second month of the season, it's a good time to see who's doing the best work on the defensive end, and Heyward is in the overall top slot in the Major Leagues, according to several of the most widely respected statistical metrics.
And he isn't the only one flashing serious leather.
Before we delve into how awesome each one of these players has been, it's important to note that the numbers represent assertions backed up by numbers. They are not yet facts.
As the science of quantifying defensive value in baseball continues to grow, the stats will continue to spawn discussions and, yes, arguments, about what the numbers show and what we can see with our eyes.
So given all that, who are the best defenders in baseball, according to the numbers?
It depends on who you're asking.
Ultimate Zone Rating (UZR), developed by Mitchel Lichtman, quantifies the number of runs a fielder is above or below average, according to FanGraphs.com, where the stats are accessible, by combining "range runs" -- "the number of runs above or below average a fielder is, determined by how the fielder is able to get to balls hit in his vicinity" -- and "error runs," defined as "the number of runs above or below average a fielder is, determined by the number of errors he makes as compared to an average fielder at that position given the same distribution of balls in play."
According to UZR entering Tuesday, Heyward, who won a Gold Glove Award in 2012, is far ahead of anyone else in the game at 13.0, with Royals left fielder Alex Gordon (9.2), Trout (7.7), Donaldson (7.3) and Marlins outfielder Giancarlo Stanton (6.8) rounding out baseball's overall top five.
And to show how far these stats have come, it's fascinating to see the top five in another respected metric, Defensive Runs Saved, developed by The Fielding Bible's John Dewan.
Dewan's company, Baseball Info Solutions, employs "scouts" who pore over video of every game played in the course of a 162-game MLB season and track each batted ball. They are tasked with analyzing how hard balls are hit, how close or far they are from the fielders deemed to be responsible for making the plays, and the result of those plays. The company comes up with a number, plus or minus, of how many runs per season a fielder "saves" or "costs" his team.
It doesn't always work out this way, but DRS looks a lot like UZR so far in 2014. Heyward leads the pack with 16 runs saved, and he is followed by Tulowitzki, Gordon, Donaldson and Stanton. Trout has saved six runs, according to these numbers, which has him tied for 12th in MLB.
What does it mean? It's hard to say when a lot can change over the course of the next 120 or so games, but it's clear that these players are off to great starts.
"Defensive stats are not perfect, but they're getting more refined," Eno Sarris of FanGraphs.com said. "It's a little volatile year to year, but so is any stat."