Now that the World Series is over and the Red Sox are coronated, it's time for Hot Stove season. Free agency is getting underway, and all 30 teams are seeking out the players who will help them fight for a championship in 2019.
When clubs are evaluating free agents as a potential fit, they'll be looking beyond just the box score. They'll be looking for tools, too -- players with power, speed, velocity, range. That's where Statcast™ comes in. The tracking data Statcast™ provides showcases players with those great tools.
So as we did last year, MLB.com is breaking down the elite tools of the 2018-19 free-agent class. (One important note: we're sharing what has happened, which can be very different from age-related projections about what may happen in the future.)
First, a few Statcast™ terms you'll need to know.
Expected Weighted On-Base Average (xwOBA): Our quality-of-contact metric, which takes the exit velocity and launch angle of every batted ball, as well as strikeouts and walks. The 2018 MLB average xwOBA was .311. Read more about xwOBA here and see the leaderboards for hitters and pitchers here.
Sprint Speed: Our footspeed metric, which measures a player's speed in feet per second over his fastest one-second window of a run. MLB average sprint speed is 27 ft/sec, and 30 ft/sec is elite. Read more about Sprint Speed here and see the leaderboard here.
Outs Above Average (OAA): Our range-based metric for outfield defense. Read more about Outs Above Average here and see the leaderboard here.
Now, let's take a look at the players entering free agency this winter.
The hitter with the best quality of contact
2018 -- Steve Pearce: .398 xwOBA
2015-18 -- Nelson Cruz: .394 xwOBA
Pearce, the World Series MVP, had the fifth-best expected wOBA in the Majors this season, out of more than 300 hitters who had at least 250 plate appearances. So maybe his Fall Classic performance wasn't so out-of-the-blue, after all. Pearce's impressive contact quality could once again make the 35-year-old a fit for a team seeking a right-handed bat who can mash left-handed pitching, as the Red Sox were when they acquired him in June. He's already proven how valuable he can be to a contender looking for a matchup edge.

Cruz has stayed remarkably consistent at age 38. He had a .394 xwOBA this season, ranking seventh in MLB, just a few points behind Pearce but sustained over more than twice the plate appearances. Cruz's overall xwOBA from the four seasons of Statcast™ tracking? Also .394. Yes, it's exactly the same as his 2018 mark -- and the best among the free-agent class, just ahead of Josh Donaldson (.391). Cruz and the 32-year-old Donaldson are both top-10 hitters in baseball since 2015 by xwOBA.
Cruz also has 247 barrels since 2015 -- those are balls hit with ideal combinations of exit velocity and launch angle -- ranking second in MLB behind only J.D. Martinez. Cruz had 60 barrels in 2015, 72 in '16, 60 in '17 and 55 in '18, ranking among the MLB leaders every year. He has the home run totals to match, with 163 homers from 2015-18 (44, 43, 39 and 37 in each season, respectively). Cruz's clockwork production will make him an interesting bet for a team in need of a big bopper, even in his late 30s.

The hitter who hits the ball the hardest: Manny Machado
257 hard-hit balls, 60 barrels in 2018
Machado is coming off a career year. He hit .297/.367/.538 with 37 home runs -- and his underlying numbers are just as good. Machado had the most hard-hit balls of any player in baseball this season. Statcast™ defines "hard-hit" as an exit velocity of at least 95 mph, and Machado had 257 batted balls that met that threshold. It's his second straight year leading the Majors in hard-hit balls, after he had 250 in 2017. Machado also had 60 barrels this year, sixth most in MLB and the most of any free agent. A team is going to have to break the bank to sign him, but they'll be getting a superstar hitter.

The most productive starting pitcher
2018 -- Hyun-Jin Ryu: .268 xwOBA
2015-18 -- Dallas Keuchel: .286 xwOBA
The 31-year-old Ryu is a free agent for the first time since he came to the Majors from Korea in 2013. In the final season of his contract with the Dodgers, he again showed he can be highly effective when healthy. That makes Ryu an interesting free-agent option despite his injury issues. He spent a large chunk of 2018 on the disabled list, but in his 15 starts, he had a 1.97 ERA, and that was supported by his contact quality allowed. Of the 168 starting pitchers who faced at least 250 batters in 2018, Ryu's .268 xwOBA was 10th-lowest. That put him just slightly ahead of other notable free-agent starters like Patrick Corbin (.281), Charlie Morton (.282) and Nathan Eovaldi (.283).
If you go back to the beginning of Statcast™ tracking in 2015, Keuchel has the most sustained track record of success. He limits contact quality by getting tons of ground balls -- which, of course, have far less potential to do damage than balls in the air. Keuchel has generated a 60.1 percent ground-ball rate since 2015, third highest among 221 starting pitchers with 500-plus batted balls against them over that timeframe. The Astros command artist is tied for the 15th-lowest xwOBA since 2015 out of that 221-starter group.

The most productive relief pitcher
2018 -- Adam Ottavino: .229 xwOBA
2015-18 -- Andrew Miller: .232 xwOBA
Ottavino came out of nowhere to become the Rockies' best reliever in 2018, with a 2.43 ERA and 112 strikeouts in 77 2/3 innings over 75 appearances. Even pitching his home games at Coors Field, Ottavino did an excellent job of limiting opposing hitters' quality of contact with his wipeout sinker-slider combo. The 32-year-old right-hander had a 35.0 percent strikeout rate in plate appearances ending on his slider, and a 40.6 percent strikeout rate in plate appearances ending on his sinker. Ottavino's .229 xwOBA allowed was the sixth-best mark among 223 relief pitchers who faced at least 150 batters this season.
Miller's performance suffered in 2018 as he dealt with knee and shoulder injuries. But the 33-year-old left-hander was one of the game's most dominant relief aces in the preceding seasons. His .232 xwOBA since 2015 is second lowest among relievers, behind only Kenley Jansen's .220.

The pitchers who miss the most bats
SP -- Patrick Corbin: 34.7 percent whiff rate in 2018
RP -- Craig Kimbrel: 40.0 percent whiff rate in 2018
Corbin, maybe the top starter on the market, will draw a lot of interest from teams like the Yankees who are looking to boost the front of their rotation. The left-hander is just 29 years old and coming off a breakout year with the D-backs in which he had a 3.15 ERA and racked up 246 strikeouts. Hitters missed on more than a third of the swings they took against him, the third-highest rate among starting pitchers behind only Chris Sale and Blake Snell. That's thanks to Corbin's wipeout slider. He got 387 swings-and-misses, and 195 strikeouts, on that pitch alone -- both far and away the most of any pitcher.

Kimbrel's combination of a high-90s fastball and a devastating knuckle-curve helped the 30-year-old Red Sox closer miss bats 40 percent of the time in 2018, the third-highest rate among relief pitchers. Kimbrel's method of getting swings-and-misses: fastballs up, and curveballs down-and-away (from the perspective of a right-handed hitter). Having an elite whiff rate is a big plus because it means Kimbrel isn't as vulnerable to bad defense or batted-ball luck as a more contact-oriented pitcher.
The best outfield range
2018 -- A.J. Pollock: +6 Outs Above Average
2016-18 -- Cameron Maybin: +8 Outs Above Average
There's not an elite outfield defender on the free-agent market like Lorenzo Cain a year ago, but Pollock was well above average in 2018 with his +6 Outs Above Average headlining the outfielders in this free-agent class. The 30-year-old can cover ground, averaging a 28.2 feet per second sprint speed in 2018 (MLB average is 27), and he's young enough to have plenty left in the tank. Maybin, who also has good speed (28.6 feet per second sprint speed in 2018), has a slight edge in his cumulative OAA rating over the past three seasons.

The strongest outfield arm: Carlos Gomez
96.1 mph average "max-effort" arm strength in 2018
The 32-year-old Rays right fielder can really air it out. Gomez's 96.1 mph average arm strength on "max-effort" throws (that's just a player's top 10 percent, to avoid counting all the lobs outfielders make back to the infield) ranked fifth among MLB outfielders in 2018. He tops a pretty deep crop of free-agent outfielders that also includes Carlos Gonzalez (95.6 mph), Leonys Martin (95.6 mph), Melky Cabrera (94.7 mph), Heyward (94.4 mph) and Bryce Harper (93.4 mph).
The strongest arm behind the plate: Martin Maldonado
87.5 mph average "max effort" arm strength in 2018
Maldonado played an important role for the Astros on their run back to the postseason after Houston acquired him from the Angels in July. The 32-year-old veteran backstop could do the same in 2019 as a valuable asset for any team looking to better control the running game. Maldonado's average arm strength on max-effort throws was the third highest among catchers. That translated to a 1.97-second average pop time to second base on steal attempts, cleanly above the 2.01-second MLB average. Maldonado's arm strength and pop time are clearly the top of the free-agent class, well better than other notable catchers like Yasmani Grandal (80.8 mph, 2.04 seconds) or Wilson Ramos (82.3 mph, 1.99 seconds).

The fastest runner: Rajai Davis
29.3 ft/sec average sprint speed in 2018
The veteran Davis continues to have top-tier speed even at 38 years old. The Indians recognized the value of that speed when they included Davis on their postseason roster for the 2018 ALDS. Davis continues to defy his age -- he was the third-fastest player over 30 this past season, and the fastest over 35. His 29.3 feet per second average sprint speed was a lot closer to the elite 30-plus feet per second range than the 27 feet per second MLB average. This isn't exactly a free-agent class loaded with speedsters. The next-fastest players: Craig Gentry (28.9 feet per second), Maybin (28.6 feet per second), Pollock (28.2 feet per second), Gomez (28.0 feet per second) and Jose Iglesias (28.0 feet per second).
An undervalued hitter: Logan Morrison
.339 xwOBA / .284 actual wOBA in 2018
After slugging 38 homers for the Rays in 2017, Morrison's production plummeted after signing with the Twins last offseason. He hit just 15 homers, his OPS dropped from .868 to .644, and Minnesota declined to pick up his option for 2019. But the 31-year-old's underlying numbers tell a different story. Morrison's xwOBA was 55 points higher than his actual wOBA, the largest "unlucky" gap of any hitter with 250 plate appearances. His contact quality was actually above average -- the overall MLB xwOBA was .311 for 2018. A team that takes a flier on Morrison might be rewarded with a much more dangerous hitter than what showed up in his on-field results this season. One other bounceback candidate in the free-agent hitter pool: Neil Walker, whose 42-point gap between his .334 xwOBA and .292 wOBA was sixth largest in MLB.
An undervalued pitcher: Marco Estrada
.329 xwOBA / .360 actual wOBA in 2018
Estrada's ERA ballooned to 5.64 in 2018, his highest in a full season. The 35-year-old's contact quality metrics weren't exactly great, but they also weren't as bad as his results. Estrada had the eighth-largest gap between xwOBA and wOBA of the 168 pitchers to face 250-plus batters this season. If that returns toward normal in 2019, Estrada might still be useful to a team needing rotation depth.
Two other pitchers with large "unlucky" gaps who could provide good value in 2019: Carsten Sabathia (.313 wOBA, .287 xwOBA) and Matt Harvey (.329 wOBA, .308 xwOBA). Sabathia, especially, had an impressive xwOBA, as the 38-year-old veteran pitched to the edges at a high rate and got a lot of weak contact (he had the fourth-lowest hard-hit rate allowed among pitchers with 200-plus batted balls against them).

A long-term bet on stuff: Garrett Richards
2,602 rpm four-seam spin rate / 3,252 rpm curveball spin rate in 2018
Richards had Tommy John surgery this summer and won't be back on the mound until 2020. But the 30-year-old right-hander has flashed some of the most electric stuff in baseball in his career with the Angels. Richards has elite spin rate on both his fastball and curveball. His average four-seam spin rate, 2,602 rpm, was second highest among MLB starters behind only Justin Verlander this season. (Richards also averaged 95.8 mph with his four-seamer, giving him a rare velocity-spin combination.) His average curveball spin rate, 3,252 rpm, was the highest of any pitcher, starter or reliever. High-spin fastballs get more swings-and-misses; high-spin curveballs tend to get more movement and better outcomes.

That's the type of stuff that should make a team want to sign Richards and give him time to recover, similarly to how the Rays signed Eovaldi as he recovered from Tommy John surgery in the offseason of 2017. Eovaldi returned this season, still throwing triple-digit heat, and following his trade to the Red Sox was a huge part of Boston's World Series-winning pitching staff. Eovaldi is a free agent again this offseason, too, and one of the top starting pitchers available.