Analytical information isn't always easy to come by in the Arizona Fall League. It's why MLB Pipeline so often relies on scouts in attendance as well as services like TrackMan to help provide the measureables (e.g., velocity, home-to-first times, catcher pop times, etc.) we use in our AFL game stories.
Statcast™ data is available for games at Salt River Fields, the Spring Training home of the D-backs and Rockies and the AFL home to the Salt River Rafters. The only caveat is that Salt River is one of six fields used in the Fall League, meaning lists of the top performances are often skewed, for better or worse, toward the players with the largest sample sizes at that ballpark.
For that reason, Statcast™ data from the AFL should be taken with a grain of salt and by no means be viewed as a sure-fire predictor of future success.
At the same time, such raw data can still effectively shine light on certain physical tools, giving evaluators a general idea about whether a player is capable of the type of physical feats that are commonplace in the Major Leagues.
Below is a look at the players who ranked near the top in four different Statcast™ categories for the 2018 Arizona Fall League.
AFL top exit velocities (in mph)
116.4 -- Daniel Johnson, Nationals (groundout)
116.3 -- Peter Alonso, Mets (double)
114.8 -- Sam Hilliard, Rockies (home run)
114.7 -- Trent Giambrone, Cubs (single)
114.6 -- Monte Harrison, Marlins (single)
113.8 -- Peter Alonso, Mets (home run)
113.5 -- Darick Hall, Phillies (single)
112.9 -- Jaylin Davis, Twins (double)
112.5 -- Austin Allen, Padres (lineout)
111.8 -- Jazz Chisholm, D-backs (home run)
MLB Pipeline No. 1 overall prospect Vladimir Guerrero Jr.'s 117-mph double, as recorded by TrackMan, off the left-field fence during the Fall Stars Game likely will be remembered as the hardest-hit ball of the 2018 AFL season. However, it was Nationals No. 7 prospect Daniel Johnson who posted the Fall League's highest recorded exit velo on Oct. 10 at Salt River Fields on a groundout to shortstop.
Johnson, 23, batted .145 over 18 games in the Fall League this year, but still made a major impression with his raw tools. In addition to showing pop in his left-handed bat, he also showcased elite sprint speed at 30.7 feet per second (above 30 is elite) while running to first base on the same play.
The only player to appear twice on the above list is Alonso, who recorded his 116.3-mph double and 113.8-mph home run in the same game on Oct. 24. Alonso not only hit his double harder than any ball hit by a Mets player in 2018, but harder than any ball a Mets player has hit since Statcast™ started tracking data in '15.

The Mets' No. 2 prospect (No. 58 overall) finished tied for first with six AFL home runs -- seven including the booming solo shot (110-mph exit velo) he hit off Nate Pearson (on a 103-mph fastball) to center field in the Fall Stars Game.
White Sox No. 1 prospect Eloy Jimenez (No. 3 overall) set the Statcast™ record for exit velocity in the AFL in 2016, when he blistered a ground ball at 119.4 mph. After that, it's this year's top four -- Johnson, Alonso, Hilliard and Giambrone -- rounding out the top five spots on the all-time list.
Top fastball velocities (in mph)
100.9 -- Justin Lawrence, Rockies
100.5 -- Justin Lawrence, Rockies
100.5 -- Justin Lawrence, Rockies
100.4 -- Justin Lawrence, Rockies
100.4 -- Nate Pearson, Blue Jays
100.2 -- Nate Pearson, Blue Jays
100.1 -- Nate Pearson, Blue Jays
100.0 -- Justin Lawrence, Rockies
99.8 -- Justin Lawrence, Rockies
99.8 -- Nate Pearson, Blue Jays
Those who tuned into the Fall Stars Game saw Pearson, the Blue Jays' No. 4 prospect (No. 90 overall), push the radar gun up to 104 mph while consistently hitting 103 during an eye-popping first inning. Forrest Whitley (Astros' No. 2, No. 8 overall) and Angels righty Brett Hanewich also hit triple digits in the game, while Melvin Adon's (Giants' No. 19) fastball topped out at 102.
Outside of that game, the top four fastball velocities in this year's Fall League belonged to Lawrence (Rockies' No. 17), whose 100.9-mph heater on Oct. 27 was the AFL's top recorded velocity in a regular-season game since Mauricio Cabrera threw 103.1 in 2015. Lawrence occupies six of 10 spots on the list, while the remaining four belong to Pearson.
If we turn on the Lawrence/Pearson filter, Dauris Valdez (Padres), a 6-foot-8 right-hander, stands out as the only hurler to appear inside the top 20 on the Statcast™ leaderboard after throwing three fastballs that registered at either 99.6 or 99.7 mph.
Top spin rates (four-seam fastball; in rpm)
2,872 -- Darwinzon Hernandez, Red Sox
2,841 -- J.B. Bukauskas, Astros
2,823 -- J.B. Bukauskas, Astros
2,804 -- J.B. Bukauskas, Astros
2,801 -- J.B. Bukauskas, Astros
2,775 -- J.B. Bukauskas, Astros
2,769 -- J.B. Bukauskas, Astros
2,766 -- J.B. Bukauskas, Astros
2,763 - Jesus Tinoco, Rockies
2,769 -- J.B. Bukauskas, Astros
Scouts have long wondered how Hernandez's stuff might translate in short bursts out the bullpen, and in this year's AFL, the Red Sox's No. 7 prospect showed it translates quite well. He posted the top four-seam fastball spin rate and consistently blew away hitters with 97-98-mph velocity, finishing with a 1.59 ERA and 24 strikeouts in 11 1/3 innings across eight appearances for Mesa.
Meanwhile, it's fair to wonder whether Bukauskas, as an undersized right-hander with an electric, high-spin-rate heater at 97-98 mph and a wipeout slider in the upper 80s, might be best suited for a bullpen role long term. In six starts for Scottsdale, the Astros' No. 8 prospect compiled a 3.33 ERA with 24 strikeouts and 10 walks in 24 1/3 innings.

Also finishing in the Top 20 in the category were Erasmo Pinales (Astros, 2,745 rpm), Nolan Long (Dodgers, 2,742) and Devin Smeltzer (Twins, 2,741).
Top spin rates (curveball; in rpm)
3,239 -- Trent Thornton, Blue Jays
3,235 -- Trent Thornton, Blue Jays
3,231 -- Trent Thornton, Blue Jays
3,227 -- Jordan Sheffield, Dodgers
3,217 -- Jordan Sheffield, Dodgers
3,207 -- Jordan Sheffield, Dodgers
3,193 -- Trent Thornton, Blue Jays
3,143 -- Darwinzon Hernandez, Red Sox
3,113 -- Jordan Sheffield, Dodgers
3,121 -- Trent Thornton, Blue Jays
The nasty curveball that Thornton showed out of Scottsdale's bullpen surely caught the attention of the Blue Jays, as they acquired him from Houston earlier this week, just days after the AFL season's completion. That pitch, paired with a 93-95-mph fastball, gives the right-hander a chance for success as either a starter or reliever.
Sheffield's (Dodgers' No. 26) best curveballs trailed Thornton's only slightly in terms of spin rate, and he showed the ability to set up the pitch with a fastball that was consistently 96-97 mph out of the bullpen.
Hernandez's appearance on both spin-rate leaderboards suggests he might own the best two pitches in the Fall League. Long (2,930 rpm) also checks in on both leaderboards, while Marlins No. 17 prospect Jordan Yamamoto (2,920) and Reds righty Wyatt Strahan (2,911) are both inside the top 20 on the Statcast™ leaderboard with their respective curveball spin rates.