Statcast of characters on free-agent market

The 2017 World Series is in the books, and the final standings look something like this: One team on top of the world (Astros); one disappointed league champion (Dodgers); and 28 teams and fan bases thrilled to finally get the offseason going.
While the baseball season might be over, the Hot Stove season is just beginning, and that means free agency is here.
• Hot Stove Tracker
Free agents can now sign with all 30 teams. Clubs are looking to fill holes or upgrade areas of weakness, but they're also looking for skills, like speed, velocity or power -- the kinds of things that they can (and do) use Statcast™ to measure.
You don't need to be in a front office to find those skills, however, because we can share them here. (A brief but important note that we are sharing what has happened, which can be very different from age-related projections about what may happen in the future.)
We'll find those skills available in the upcoming free-agent market and share them with you here, but first, a few Statcast™ terms you'll need to know.
Expected Weighted On-Base Average (xwOBA): Our quality-of-contact metric, which accounts both for defense-independent outcomes of batted balls based on exit velocity and launch angle as well as strikeouts and walks. The 2017 MLB average xwOBA was .314. Read more about xwOBA here and see leaderboards for hitters and pitchers here.
Sprint Speed: Our foot-speed metric, which is displayed in "feet per second [in a player's fastest one-second window]," where 27 feet per second is average and 30 feet per second is elite. Read more about Sprint Speed here and see the leaderboard here.
Outs Above Average (OAA): Our outfield defense range metric, OAA. Read more about Outs Above Average here and see the leaderboard here.
So, you're looking for …
The hitter with the best quality of contact
2017: J.D. Martinez, .423 xwOBA
2015-17: Martinez, .402 xwOBA

Though Martinez made waves with his massive power production after being traded to Arizona (he hit 29 homers in 62 games with the D-backs), don't let anyone pretend he wasn't elite before that, too, as his .431 xwOBA with Arizona was only slightly better than his .415 Detroit mark. For this category and all others to follow, teams aren't just going to look at one year of data, but even going back to 2015, Martinez has the seventh-best wOBA production of the 232 hitters with at least 1,000 plate appearances. And in '15, he led the Majors with 74 barrels. No one in this free-agent class -- not Eric Hosmer or Todd Frazier or Jay Bruce -- matches up at the plate.
The most productive starting pitcher

2017: Yu Darvish, .291 xwOBA
2015-17: Jacob Arrieta, .277 xwOBA
It's actually a solid class for starters, with Arrieta, Lance Lynn, Alex Cobb, Carsten Sabathia, Jaime Garcia and others, but it's Darvish who stands atop the list, especially since his midseason trade to Los Angeles means he can't be saddled with a qualifying offer. Ignore the 10-12 record, much of which came with a below-.500 Texas team; it does not matter. Arrieta, meanwhile, will be an interesting case, as his metrics both traditional (ERA up from 1.77 to 3.10 to 3.53) and advanced (xwOBA up from .242 to .293 to .301) have been going the wrong way since his stellar 2015, but even his .301 xwOBA mark from this year is comfortably above average.
The most productive relief pitcher

2017: Pat Neshek, .216 xwOBA
2015-17 (minimum 100 innings): Neshek, .250 xwOBA
Let it be said right away that Neshek, the 37-year-old sidearmer, will absolutely not be getting the largest bullpen contract this offseason. Neshek is older than Wade Davis (.289 xwOBA) and Greg Holland (.270 xwOBA), who will each be 32 in 2018, he averages just 90 mph on his fastball, and he doesn't come with the "proven closer" label that Davis and Holland each have. That said, Neshek has shown repeatedly that he can pile up whiffs and limit walks (69/6 K/BB this year) as well as prevent hard contact, particularly when he's asked to face right-handed hitters: He had a .183 xwOBA against righties in '17, and a still impressive .266 mark against lefties.
In addition to Neshek and the two big names mentioned above, keep an eye out for a pair of 2017 breakout relievers: righty Brandon Morrow (.240 xwOBA, 50/9 K/BB) and lefty Mike Minor (.238 xwOBA, 88/22 K/BB).
The best outfield range

2017: +15 OAA, Lorenzo Cain
2016-17: +27 OAA, Cain
Need to add some defense to your outfield? The obvious choice here is Cain, who has been patrolling Kansas City's large outfield with elite skill for years, befitting his position as one of baseball's fastest players, and it's easy to see teams like the Giants or Mets showing interest. While he turns 32 in April, he's starting from such a high level that even some expected age-related decline wouldn't crater his value, and this isn't really a strong outfield defense class anyway. Cain's former teammate Jarrod Dyson (+7 OAA in an abbreviated season) is older than Cain, at 33, and the rest of this group features players like Martinez, Melky Cabrera, and Jose Bautista, who no longer count defense as a strength.
The fastest runner
2017: Rajai Davis, 29.2 feet per second

We'll call this basically a three-way tie, since Cain (29.1 feet per second) and Peter Bourjos (29 feet per second) were right up there with Davis, who, at 36 years old in 2017, was trying to singlehandedly disprove the evidence that speed peaks young by finishing as a top-10 speedster in baseball. Even as a part-time player with Oakland and Boston, Davis still stole 29 bases -- his 11th straight year with at least 18 swipes.
The strongest outfield throwing arm

2017: Carlos Gonzalez, 94.8 mph
2015-2017: Carlos Gomez, 95.9 mph
Though Gonzalez had a disappointing season at the plate, he retained the strong throwing arm that Rockies fans have been seeing for years. (The 94.8 mph we're showing here is not the average of all his throws, given how many are non-competitive lobs, but are instead the average of his "max-effort" throws, defined as the top 10 percent of his hardest throws.) If we go back over the past three years, however, Gomez just barely tops Gonzalez, and Gomez was one of only seven outfielders with a throw tracked at 100 mph in 2017.
An undervalued batter
Hyun Soo Kim, .274 wOBA / .321 xwOBA

By looking at what a batter's quality of contact indicates his results might have been (xwOBA) and seeing the difference from what his results actually were (wOBA), we can try to get to the underlying skills that tell a truer story than the outcomes, just like we did when looking at Manny Machado's slow first half.
It's with that in mind that we point out Kim, who followed up a successful debut (.302/.382/.420) with a disappointing sequel (.231/.307/.292) that included surprisingly being traded to the Phillies, where he was mostly buried on the bench. That said, his quality of contact indicated that he deserved more of a league-average line than the one he put up. His hard-hit rate of 36 percent held steady (and was slightly above the Major League average), and his percentage of batted balls that were flies or liners actually went up from 43 percent to 48 percent. Kim will almost certainly be available on a Minor League deal, and he could add value as the lefty side of a platoon. (And he's very much a platoon player, having received just 33 at-bats against southpaws in two MLB seasons, with just two hits against them.)
An undervalued pitcher
Anibal Sanchez, .386 wOBA / .329 xwOBA

It may sound odd to say that there's value in a pitcher who had a 6.41 ERA this year and a 5.87 ERA in 2016, but that's sort of the point; players coming off strong seasons aren't exactly hidden gems. For Sanchez, there were some signs of life around his poor season, as the advanced quality of contact stats suggest a league-average pitcher, rather than a disastrous one. His 21.6-percent strikeout rate was exactly the MLB average; his six-percent walk rate was two points better than average.
After missing time in August with a hamstring issue, Sanchez came back to have one awful start (seven earned runs in 4 2/3 innings in Toronto) and four strong ones (31/7 K/BB, 2.74 ERA in 23 innings). While he allowed too many homers, he was also hurt by Detroit's weakest-in-the-AL defense, and after his 2018 option was declined, Sanchez may be in line only for a Minor League deal. He's not someone you rely on, but there's more there than that high ERA.
A bet on spin rate
Tyson Ross's four-seamer, 2,557 rpm (second highest among 223 starters with 100 thrown)
Tyler Chatwood's curve, 2,972 rpm (fourth highest among 149 starters with 100 thrown)

It's important to note that spin, by itself, does not create success. After all, neither Ross nor Chatwood had terribly strong years in 2017. But you could say the same thing about velocity, of course, and teams have been betting they could turn hard-throwers into productive pitchers for decades. It's a tool that can be used to get to success, rather than being the sole reason for it.
With the right team, with the right coaches, and with some better circumstances -- health in Ross' case, leaving Coors Field for Chatwood -- it's easy to see someone taking a bet that they can take this raw skill and make a valuable pitcher out of it, just as the Astros did with Collin McHugh several years ago. Chatwood, in particular, seems to be an appealing breakout option.