Seattle's Gordon is MLB's fastest man by one measure

We don't know exactly how Dee Gordon will look as the Mariners' center fielder in 2018. After all, he's never played a game outside the middle infield in his Major League career. But we do know this: He's more than fast enough to handle the position.
There's a lot more to playing center field than raw speed, but Gordon's elite speed gives him a much higher baseline than most players would have for a transition to the position that requires more range than any other.
Gordon's Statcast™ data can help gauge how he might handle the transition. The data for Gordon in the outfield doesn't exist yet, and a player doesn't get much chance to ramp up to top speed while playing the infield. But what we do have is the data for Gordon's speed on the bases, and those numbers are top-tier.
Start with Gordon's average max-effort Sprint Speed: 29.7 feet per second, which ranked him as the fourth-fastest player in the Majors last season. (Sprint Speed measures a player's speed over his fastest one-second window running the bases.) The only three faster players were center fielders -- Byron Buxton (30.2 feet per second), Billy Hamilton (30.1 feet per second) and Bradley Zimmer (29.9 feet per second) -- placing Gordon in the company of some of the top defenders at the position.
A good marker of the degree to which Gordon can make a difference is how fast he gets down the first-base line. Going from home to first isn't the same as running down a ball in the gap, but it shows his straight-line speed and his ability to eat up ground.
In 2017, Gordon separated himself from the pack in those first 90 feet. Four seconds is a quick and easy dividing line for top-end speed -- only the fastest runners post sub-4.00 home-to-first times on a regular basis. Gordon was in a league of his own in that category.

Statcast™ tracked Gordon as going home to first in less than four seconds 123 times last season. He nearly doubled up the next-closest player, Hamilton, who had 69 sub-4.00 home-to-first times. Buxton was third, with 36. Times like those turn outs into hits -- Gordon led the Majors in ground-ball hits by a wide margin, with 101 to runner-up Jose Altuve's 87.
Most sub-4-second home-to-first times in 2017
1. Dee Gordon: 123

2. Billy Hamilton: 69
   
3. Byron Buxton: 36
   
4. Delino DeShields: 30
   
5. Mallex Smith: 28
   Part of the huge disparity in sub-4.00 home-to-first times between Gordon and the others is likely due to the fact that he is exclusively a left-handed hitter, which gives him a head start toward first; Buxton is a righty and Hamilton is a switch-hitter. Another part is opportunity. Gordon put more balls in play than the other two, and he didn't just lead the Majors in ground-ball hits, he led the Majors in ground balls, period, and they're the type of batted ball where a hitter is most likely to bust it down the line.
   But Gordon was right at the top of the sub-4.00 list on a rate basis, too. He went home to first in less than four seconds on 36.9 percent of his tracked runs overall, and on 46.1 percent of his ground balls. The only player with at least 10 tracked runs and ground balls and a higher rate of sub-4.00 times in those categories was Magneuris Sierra -- but the then-Cardinals rookie had fewer than one-tenth of the tracked runs and ground balls that Gordon did.
   By comparison, Hamilton went home to first in less than four seconds on 21.5 percent of his total tracked runs and 34.7 percent of his ground balls. Buxton had sub-4.00 home-to-first times on 17.5 percent of his tracked runs and 33.3 percent of his grounders.
   Highest sub-4-second home-to-first rate on ground balls in 2017
   Minimum 10 tracked runs
   
6. Magneuris Sierra: 56.5 percent
   2. Dee Gordon: 46.1 percent
   
7. Emilio Bonifácio: 37.5 percent
   
8. Brett Phillips: 35.0 percent
   
9. Billy Hamilton: 34.7 percent
   That doesn't prove that Gordon will be able to track down every tough fly ball, especially early on. But there's one recent comparison to make that's encouraging, and that's to Washington's Trea Turner.
   Turner went from playing middle infield to playing center in 2016, then returned to shortstop last year, so there's Statcast™ data for him both on the bases and in the outfield. Turner was successful for the Nationals in center, worth 4 Outs Above Average in '16, according to Statcast™. That put him in the top 20 percent of qualified outfielders. He made two 5-Star catches -- the most difficult level of catches, with a catch probability of 25 percent or less -- and converted four of five 4-Star opportunities, which have a catch probability of 26-50 percent.
   Turner acquitted himself well in the outfield, and like Gordon, he is an upper-echelon speedster. But Gordon has been just as fast, if not faster. His 29.7 feet per second Sprint Speed in 2017 edged out Turner's 29.2 feet per second. In '16 they were even at 29.5 feet per second.
   So if Turner can do it, there's good reason to think Gordon can do it, too. We'll see when the first results of the experiment start coming in on Opening Day.