Fantasy Baseball Prospects Report: From Justus Sheffield to Jesus Luzardo, long-term stashes nearing payoff as September approaches

If it feels like baseball season is beginning to wind down, well, that goes double for the minor leagues. In fact, they're down to their final two weeks of regular-season play.

Some teams will advance to postseason play, of course, so it's not like every potential September call-up has nothing better to do. But with major-league rosters also expanding at that point, it makes for a natural transition for many.

Might "many" include some of the impact prospects we've been stashing for months on end? Going by the word of relevant beat reporters, it might indeed.

If nothing else, it'll all come to a head soon, so let's take one more look at those prospects to get a sense of where things stand, beginning with the one we already know to be on his way.

Five on the verge

(These are the prospects most worth stashing in redraft leagues.)

Justus Sheffield, SP, Mariners

2018 minors: 7-6, 2.48 ERA, 1.14 WHIP, 116 IP, 50 BB, 123 K 
2019 minors: 7-9, 4.13 ERA, 1.35 WHIP, 133 IP, 59 BB, 133 K
      

Yes, Sheffield is coming up to make his first major-league start (he has appeared four times in relief already) Friday, and I shared some initial thoughts on his impending promotion in my most recent look at the waiver wire. Since then, we've gotten more assurances from manager Scott Servais, who said the Mariners would prefer to let work Sheffield through his issues than shuttle him to and from the majors.

 "We'd like to call him up and leave him here and let him go," Servais told MLB.com.

And that's great news, especially given that Sheffield has already set a career high for innings pitched. It sounds like he should still have a handful of starts left in the bag. He also looks now like a better pitcher than the one who came up for short stints previously, actually living up to his lofty pedigree with a 2.19 ERA, 1.03 WHIP and 9.8 K/9 in 12 starts at Double-A. He commanded his arsenal much better, making him efficient enough to throw seven innings at a time, and seeing as he's been a fixture in the Baseball America top 100 for four straight years, that's an exciting development indeed.

Gavin Lux, SS, Dodgers

2018 minors: .324 BA (463 AB), 15 HR, 13 SB, .913 OPS, 57 BB, 88 K
2019 minors: .352 BA (432 AB), 25 HR, 10 SB, 1.044 OPS, 59 BB, 97 K
             

Totally playing a hunch here, but I think the Dodgers make Lux their primary second baseman come September. For now, they're giving him a chance to present an excuse not to do it, and they can afford such an abundance of caution since they're already running away with the division. Better not to ruffle feathers and create a suboptimal financial situation if there's reason to believe the guy isn't ready. But here's what president of baseball operation Andrew Friedman recently had to tell the Los Angeles Times about the 21-year-old talent:

"He has a real maturity in the batter's box I don't think I've ever seen from someone that age," Friedman said. "It allows him to make in-game adjustments, and, boy, has it been really impressive."  

When was the last time you heard the primary decision-maker offer such effusive praise of a prospect beating down the door to the majors? Usually, the suits are having to justify their reasoning for keeping the kids down. I think if Lux is still lighting up Triple-A to the tune of a .415 batting average and 1.300 OPS by the time rosters expand, they greenlight him in the hope of another World Series run.

Jesus Luzardo, SP, Athletics

2018 minors: 10-5, 2.88 ERA, 1.09 WHIP, 109.1 IP, 30 BB, 129 K 
2019 minors: 2-1, 3.06 ERA, 0.99 WHIP, 32 1/3 IP, 5 BB, 43 K
  

How likely is it Luzardo will be called up in September? Here's an excerpt from a recent interview with GM David Forst via Shayna Rubin of The Mercury News:

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My contention has always been that Luzardo is too important to the Athletics' playoff chances, basically functioning as their ace from the get-go, to hold back once he proves fully rehabilitated from his latest injury, a strained lat. And Forst seems to confirm those suspicions, however subtly, here. Luzardo has mostly dominated on his latest rehab assignment but did have a hiccup in his first outing for Triple-A Las Vegas last week. He recovered to strike out five over 4 2/3 one-run innings last time out.

Kyle Tucker, OF, Astros

2018 minors: .332 BA (407 AB), 24 HR, 20 SB, .989 OPS, 48 BB, 84 K
2019 minors: .265 BA (434 AB), 32 HR, 29 SB, .907 OPS, 53 BB, 110 K 
         

There's little new to report on the Tucker front, though it's worth pointing out that beat writer Brian McTaggart of MLB.com has repeatedly expressed confidence Tucker would be up in September. The bigger question is what kind of role he'll have, but the way Josh Reddick has performed in the second half, batting under .200, certainly helps the cause. Like the Dodgers, the Astros have their division pretty well in hand and are the presumptive favorites for their respective league, so they'll want to assess Tucker for a possible World Series run. The 22-year-old didn't fare well in a major-league trial last year but wasn't given the most consistent playing time either. And while he has had his ups and downs in the minors this year, he's certainly on the right track now, batting .300 (21 for 70) with five homers and six steals in August. 

Luis Robert, OF, White Sox

2018 minors: .269 BA (186 AB), 0 HR, 11 2B, 15 SB, .694 OPS, 12 BB, 52 K
2019 minors: .336 BA (459 AB), 29 HR, 36 SB, 1.022 OPS, 27 BB, 118 K  
    

The biggest question mark among what I'd consider to be the most stashable prospects is Luis Robert, who continues to put up stupid across-the-board numbers at Triple-A, as he did at Double-A and high Class A earlier this season. Unlike Lux and Tucker, Robert isn't with an organization that's competing for anything, and particularly in recent years, financial considerations have tended to beat out all other factors in those situations. But there's a case to be made that if the White Sox are looking to compete next year, as many think they will be, they'll want to have a better idea of Robert's readiness heading into the offseason. And they have yet to rule anything out.

"He's doing very well. He continues to impress everyone. That's about as much as I can say," manager Rick Renteria recently told the Chicago Sun-Times. "All of us are looking forward to the time when that young man continues to progress and join the guys that are here. I wish I had a crystal ball and can tell you when that was."

Realistically, the chances of a Robert promotion this September are less than 50/50. They may not even be 1 in 4. The benefits of holding him out until a couple of weeks into next season are simply too great. But in the unlikely event he does get the call, stashing him could turn out to be the most important move you make all season.

Five on the periphery

(These are some other prospects doing something of note.)

Ryan Mountcastle, 3B, Orioles

2018 minors: .297 BA (394 AB), 13 HR, 19 2B, .806 OPS, 26 BB, 79 K 
2019 minors: .312 BA (475 AB), 24 HR, 30 2B, .872 OPS, 20 BB, 115 K
    

Mountcastle is one of those prospects whose hype always seemed to exceed the production, but in my experience, prospects who maintain that hype all the way to the upper levels tend to turn out OK. It's also worth pointing out that Mountcastle's numbers suddenly look pretty good, buoyed by him homering five times in his past 10 games, and at age 22, he may be looking at a September call-up himself. The lack of plate discipline still raises questions about his ceiling for me — and most likely, he'll be confined to first base — but he has earned the benefit of the doubt whenever his day comes.

Nate Pearson, SP, Blue Jays

2017 minors: 0-0, 0.90 ERA, 0.60 WHIP, 20 IP, 5 BB, 26 K 
2019 minors: 4-4, 1.99 ERA, 0.86 WHIP, 90 2/3 IP, 24 BB, 107 K
   

One of the biggest risers among pitching prospects this year moved up a level for the second time with his debut for Triple-A Buffalo on Tuesday. And the fact Pearson went seven innings in that start is an important step given how much the Blue Jays babied him early on — an understandable approach given that he missed almost all of last year with a fractured forearm. The strikeouts have slowed at the upper levels, which is to be expected given how hard the Blue Jays have pushed him, but he has one of the most overpowering fastballs in all the minors and could be knocking on the door to the majors as early as next year.

Mauricio Dubon, SS, Giants

2018 minors: .343 BA (108 AB), 4 HR, 9 2B, .922 OPS, 2 BB, 19 K 
2019 minors: .299 BA (479 AB), 19 HR, 26 2B, .818 OPS, 27 BB, 67 K
  

If the Giants acquired Dubon at the deadline intending to make him their starting second baseman next year, the 25-year-old has only helped his chances at his new Triple-A home in Sacramento, batting .307 (23 for 75) with three home runs in 20 games. The power breakthrough is certainly suspect in a juice ball-infused Pacific Coast League (which was hitter-friendly even before then), but the contact skills have always been there. He could become the reliable source of batting average Joe Panik never ultimately did, if not something better.

Trevor Rogers, SP, Marlins

2018 minors: 2-7, 5.82 ERA, 1.56 WHIP, 72 2/3 IP, 27 BB, 85 K 
2019 minors: 6-9, 2.55 ERA, 1.09 WHIP, 127 IP, 29 BB, 143 K
    

The 13th overall pick in 2017, Rogers didn't make much of a first impression last season, but he had hardly pitched the year he was drafted and needed to work on his secondary arsenal. Things have gone much better this time around, to the point he has advanced all the way to Double-A, where he just delivered a two-hit, 10-strikeout gem over seven innings. It was his sixth start in eight of seven-plus innings and fourth start this season with double-digit Ks, so the stuff and efficiency both earn high marks. The Marlins are stacked with exciting young pitchers right now, but it's hard to imagine Rogers won't get his shot at some point next year.

Kris Bubic, SP, Royals

2018 minors: 2-3,4.03 ERA, 1.50 WHIP, 38 IP, 19 BB, 53 K 
2019 minors: 10-4, 2.31 ERA, 0.96 WHIP, 136 1/3 IP, 39 BB, 178 K
              

The fourth of the Royals' first-round pitchers last year, drafted 40th overall, has been the most impressive statistically this year, leading all minor-leaguers in strikeouts across two levels. He's coming off back-to-back complete-game, 11-strikeout efforts, the most recent being a one-hitter. A funky delivery and ability to disguise the changeup have been the keys to his success, as well as throwing bunches of strikes. Refining his breaking ball will be paramount moving forward, but there's clearly something to work with here.

Senior Fantasy Writer

Raised in Atlanta by a board game-loving family during the dawn of the '90s Braves dynasty, Scott White was easy prey for the Fantasy Sports, in particular Fantasy Baseball, and has devoted his adulthood... Full Bio

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