Fall Flashes: Arizona Fall League Top Prospect Risers

Eric Samulski evaluates the top risers and breakout performers among prospects at the Arizona Fall League. These minor league prospects are worth stashing in dynasty fantasy baseball leagues.

Every year, some of the best minor league prospects head to Arizona to take part in the Arizona Fall League. It features six teams of prospects, sent by their organizations to get extra game reps against top-flight competition, sometimes including players at higher levels in the minor league system. Given the high level of competition, success during AFL play can often have a drastic impact on a player's professional outlook.

Below we'll take a look at some players who improved their stock based on their performances. These will not be players who already came in with fantasy owners drooling over them, which means you won't see Jo Adell, Daniel Lynch, Joey Bart, Alec Bohm or Julio Rodriguez on here.

There are some top-tier prospects whose poor seasons had sown the seeds of doubt, but many are older or lower-level prospects who showed that they might have been collectively overlooked. For each guy on the list, we'll look at his AFL stats, overall scouting profile, and when we may seem him in the major leagues. Stats for hitters are written as (AVG./OBP./SLG., HR, RBI, RUNS, SB)

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Forrest Whitley (SP, HOU) & Royce Lewis (SS, MIN)

25 IP, 22 H, 2.88 ERA, 1.24 WHIP 32:9 K:BB (ETA: 2020)

.353/.411/.565, 3, 20, 21, 5 in 22 games (ETA: 2021)

I'm grouping Lewis and Whitley together because they both came into the 2019 season as top prospects. Whitley was fifth on Baseball America's top 100 prospects, published on May 1, 2019, while Lewis was ninth. Then Lewis hit .238/.289/.376 in 94 doubles at High-A and .231/.291/.258 in 33 games at AA, and some people began to get worried about his ultimate ceiling. Similarly, Whitley seemed on the cusp of a major league call-up until he got roughed up to start the year in the minors. Even though he recovered to a certain extent, he finished the year with a 12.21 ERA in five AAA starts and a 5.56 ERA in six AA starts. His K% at AAA dropped almost 10% off of his career average, and his walk rate at both levels jumped into questionable territory.

They both came into AFL games with some level of concern and needed a strong showing to reassure scouts and fantasy players alike that their upside remained unchanged. Both were entirely successful in doing so.

For Lewis, the most important validation was his batting average and on-base percentage, which struggled mightily during the year. He will never be a consistent power bat, but he has the speed to rack up some steals if he gets on base regularly enough. His inability to hit for average or take walks in 2019 was concerning, so seeing him do both against high levels of competition was good. He still struck out 22 times in 22 games, but you can forgive him given the competition and his clear growth.

For Whitley, seeing the walk numbers kept under control was the biggest sigh of relief. When he doesn't fall behind, he's able to show off a plus change, curve, and slider to pair with his mid-90s fastball. His stretches of dominance during the AFL season were reassurance of just how high his ceiling remains and with Gerrit Cole and Wade Miley no longer in Houston, there is a chance that Whitley could see regular starts by the second half of this season.

Spencer Howard (SP, PHI)

21.1 IP, 10 H, 2.11 ERA, .94 WHIP 27:10 K:BB         

ETA: 2021

In all honesty, Howard was probably a riser during the entire 2019 campaign that saw him pitch at three different minor league levels, compiling a 2.03 ERA and an 11.9 K/9. However, what could have been explained as one strong year from a 23-year-old arm who was advanced for some of those levels, began to look a lot more legit after he carved up elite prospects with Scottsdale. Howard topped out at 99 mph with his fastball but routinely sat at 96 and demonstrated a plus slider and a change that has the potential to be plus. His strong BB% percentage in the fall backed up a ridiculous K-BB% at all levels of the minors this past season and suggests clear strikeout upside with the potential for solid WHIP.

He'll start the year at AA again, but he's proving to be a legit prospect with a chance to see AAA innings or even a cup of coffee in the big leagues this year if that changeup continues to evolve into a third weapon for him.

Andres Gimenez (SS, NYM)

.371/.413/.586, 2, 15, 11, 2 in 18 games          ETA: 2021

The 21-year-old shortstop has been a fixture on Top-100 lists, but he's always been touted as a glove-first player with impressive range and fluidity in the field but a barely mediocre bat. Across two seasons and over 150 games at AA, Gimenez was only able to hit .257 with nine HR but saved his fantasy value with 38 stolen bases. He looked like a one or two-category fantasy producer who would see consistent reps because of the quality of his glove. But then something happened in Arizona.

In 18 games, Gimenez wound up as the leading hitter in the entire league and his .999 OPS was over .300 points higher than what he put up in AA during the 2019 campaign. Against top-level competition, Gimenez seemed to raise his game and with the ability to add weight to his 160-pound frame, the potential for bankable offensive production seems tangible. He still strikes out too much for a non-power hitter - 15 in 18 games during the AFL and a 21.3 K% at AA, but if the quality of contact he showed in Scottsdale is legit then Gimenez could become a more dynamic fantasy asset then we thought with potential for a .285, 10 home run, 35 stolen base type of upside.

Geraldo Perdomo (SS, ARI)

316/.417/.418, 1, 5, 17, 2 in 21 games         

ETA: 2021

Perdomo is a lean switch-hitting shortstop who wasn't on many non-dynasty fantasy radars after spending most of 2018 in rookie ball. He showed off good wheels with 24 stolen bases, but a few scouts questioned the inflated BABIP and lack of power. While one home run in the AFL won't answer any of the concerns about his power, he did reach exit velocities up to 87 miles per hour, which shows clear growth and a suggestion that some power might be in his future. However, where Perdomo stands out most is his high batting average and ability to maintain a consistently high BB%, which suggests that Perdomo has a good feel for the strike zone and the ability to work counts in his favor.

With his plus wheels, his high contact rate allows him to earn more singles and give himself opportunities for stolen bases. Even without the power, his glove and speed can keep him as a Major League regular, but if he's able to show even 15-home run upside, he becomes a 15-HR, 30-SB candidate who will provide a solid average and on-base percentage. That's an infinitely more attractive fantasy prospect and one the Diamondbacks seem to be banking on since they're trading away all of their top minor league SS talent (such as Jazz Chisolm), aside from Perdomo.

Greg Deichmann (OF, OAK)

.256/.347/.634, 9, 20, 15, 2 in 23 games         

ETA: 2021

After covering five players who appear on most top-100 lists, it's time to start diving into guys who are not household names. Deichmann is a 24-year-old outfielder in an organization with Jorge Mateo and a few newly intriguing prospects threatening to push their way onto the major league roster.

Nobody was talking about Deichmann coming into AFL games despite stealing 19 bases in 80 games at AA. A .219 average and 30.3 K% will do that. However, there were signs that Deichmann had more in the tank. His 10.3 BB% showed a good feel for the strike zone and strong SLG% and ISO at the lower levels of the minors suggested that he had latent power. It was that power that caught people's eyes in Arizona as he led the AFL with nine home runs while posting a .982 OPS. When you pair that with the baserunning acumen he's shown, it's hard not to get a little excited.

His K% is still too high - he struck out 29 times in 23 AFL games - but if the power carries over into another season in the minors, we could be looking at a .245 hitter with 30 home run and 15-20 stolen base potential. That will play in almost any format, especially if Oakland uses its crowded talent pool as an excuse to dangle Deichmann as part of a larger trade to a better hitter's park.

Ashton Goudeau (SP, COL)

13 IP, 4 H, 0.00 ERA, .30 WHIP 18:0 K:BB         

ETA: 2020

Well, those are some stupid numbers. Sure, Goudeau is now 27-years-old and had already reached AAA in 2018 with the Mariners, but it would be foolish to write off what he did. A non-prospect who has struggled to a 4.81 ERA over eight minor league seasons, Goudeau made a major change when he came to the Rockies organization in 2019, getting rid of his slider and beginning to focus more on his curve. His first year with the Rockies showed that could be a potential career-changing alteration as he pitched to a 2.07 ERA and 30.1 K% across 16 AA starts.

Since he broke his pitching hand during the season, the Rockies sent him to the AFL where he showed off his 95 MPH fastball and that plus curveball en route to a dominant performance. It could just be a signal that a change in pitch mix has altered the trajectory of Goudeau's career. He'll likely begin the year in AAA, but if he experiences anything close to the same level of success, expect to see the Rockies give him a chance at the big league level.

Reggie Lawson (SP, SD)

11 IP, 3 H, .82 ERA, .46 WHIP 14:2 K:BB         

ETA: 2021

Oh look, another potentially strong prospect in the Padres organization. After being a second-round pick in 2016, Lawson has struggled to a 4.91 minor league career ERA, a 5.07 FIP, and a 20.5 K%, which is underwhelming for such a high draft pick at the low levels of the minors. However, something may be starting to click. Despite not having a great year in AA, Lawson's K% rose to 29.8%, his K-BB% was a career-high 19%, and his LOB% continued to rise to a career-high 70.6%. In the AFL, he showed impressive strikeout upside with a 95 mph fastball and a sharp curve.

It seems as though Lawson is becoming a more aggressive pitcher, which is unlocking some of his upside. If that can continue in 2020 then he could add his name to the list of intriguing Padres arms.

Brandon Marsh (OF, LAA)

.328/.387/.522, 2, 11, 13, 4 in 19 games         

ETA: 2021

Marsh is frequently lost in the prospect discussion because of the talent within his own organization. Mike Trout is a generational talent at the Major League level, but fast-rising Jo Adell is being touted as a future star and Jordyn Adams is becoming a name you hear on everybody's lips (or read off of the tips of their keyboards). The problem is that Marsh is not deserving of being overlooked. He might not match the upside of Adell, Marsh is a talented prospect in his own right.

While he didn't display tremendous power in the AFL, he is a consistent line-drive hitter with a repeatable swing that suggests 20 home run power could be coming. He has a strong sense of the strike zone, and his four stolen bases in the AFL suggest a smart base runner who can find ways to produce even without elite speed. His defense and arm will keep him in the lineup, and he has a solid floor to suggest fantasy goodness in multiple categories. He's not the type of player to wow you, but you'll look up at the end of the season surprised at the .280-20-15 line with strong counting stats.

Penn Murfee (SP, SEA)

22 IP, 16 H, 1.23 ERA, .96 WHIP 30:5 K:BB         

ETA: 2020

You can be forgiven for not knowing much about a 25-year-old former 33rd-round draft pick who spent most of 2019 pitching at High-A. Although Murfee pitched in five games out of the bullpen at AAA and showed strikeout upside, he also got hit extremely hard and showed inconsistent command. Those aren't credentials that really jump off the page. However, a look under the hood suggests that the control wonkiness at AAA was an illusion. Murfee had a 5.5% BB% over 102.2 innings at High-A and only walked five in 22 innings against top-level competition at the AFL. His 29.2% K% at High-A also carried over as he was second in the AFL in strikeouts.

Although he doesn't have overwhelming stuff, he mixes arm angles and spins to keep hitters off balance. Given his advanced age and recent results, it wouldn't be a surprise for Murfee to start the year at AAA with a chance to debut in the majors if the results continue.

Victor Castaneda (SP, MIL)

22.2 IP, 13 H, 1.99 ERA, .84 WHIP 29:6 K:BB         

ETA: 2022

Castaneda is probably the least-known prospect on this list after signing out of the Mexican League in 2017 at only 18-years-old. Even in his two years in the Brewers farm system, he hasn't produced stellar results. This year he pitched solely out of the bullpen, throwing 44 innings with a 4.50 ERA. However, the metrics under the surface looked a little better, as he had a 28.5 K%, a 21% K-BB%, and a 3.17 FIP. During his stint with Glendale in the AFL, Castaneda was asked to start and put up some dominant numbers. He showed good command of his fastball, splitter, and change, which suggests that he could have a potential future as a starter.

He's not a hard thrower, so he will need to use the plus command and sequencing he showed this fall to his advantage, but it's hard to ignore these numbers and this level of soft contact given up against the talent that he was facing.

Jared Oliva (OF, PIT)

.312/.413/.473, 0, 10, 18, 11 in 26 games         

ETA: 2020

Let's end with the name that been most floated in prospect circles over the last few days. After the Pirates traded away Starling Marte, everybody is wondering when we might get to see Oliva in the big leagues. A lot of that has to do with his showing in the AFL. Yes, 30+ stolen bases in each of his last two minor league seasons caught scouts' eyes before, but seeing the baserunning smarts and pure line-drive swing on display against this level of talent was even more reassuring.

Oliva makes his bread with strong contact on the ground or on the line and a real feel for the strike zone. His zero home runs reflect the larger truth we've come to see, that getting to double home runs in a season would be an added bonus, but he's a potential future .300 hitter with 30+ stolen base upside. Even if he adds 10-15 home runs to that line, he becomes a true fantasy asset.

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