The Long Game: Who's Next?

While it didn't happen exactly as everyone thought it might, Ronald Acuna received his promotion to the big leagues this week, joining prospects like Gleyber Torres, Scott Kingery, Tyler O'Neill and Lourdes Gurriel in making their MLB debuts through the first few weeks of 2018.

Whether you're playing in a keeper or dynasty format, or a re-draft league deep enough that's it's worth stashing minor leaguers who could make an impact in the majors, all these promotions naturally prompt a question. Who's next? Which kid is going to be the next one to get called up and supply an adrenaline shot of fantasy value to a needy roster?

Below is a list of prospects – some among the game's elite, some found a little further down in RotoWire's Top 400 rankings – who have at least semi-plausible paths to the Show this season. Whether they're worth picking up now depends on your league depth, available bench spots, roster needs and ability to stay patient and wait for them to get promoted, but all of these guys should probably be on your radar in case they suddenly appear in your free-agent pool.

Vladimir Guerrero Jr. / Bo Bichette, Blue Jays: It just seems right to list these two together, as they'll likely continue their ascent in the Jays' system together and it wouldn't be a surprise to see them debut as a duo, either. Both sons of former major leaguers and both in RotoWire's fantasy prospect top 10 (Guerrero at No. 2, Bichette at No. 8), Vladito has the higher ceiling and the dad with the better career, but Bo's pop was hardly a scrub. So far for Double-A New Hampshire, Guerrero is slashing .353/.407/.529 with a 7:7 BB:K as a 19-year-old, which is just flat out ridiculous, but Bichette has nearly matched his buddy, slashing .303/.376/.434 as a 20-year-old with seven steals in eight attempts and a 9:17 BB:K in 17 games. More important than their impressive tools, at least when it comes to their possible 2018 value, is that there are plausible paths to Toronto for both of them. Josh Donaldson's shoulder is balky and he's a free agent in the offseason, which puts a trade on the table to open up the hot corner for Guerrero if the Jays aren't in playoff contention – or a Rafael Devers-like debut if they are, and Donaldson's back on the DL during crunch time. As for Bichette, the Jays have already run through a half-dozen different middle infielders in a month without Troy Tulowitzki even getting an at-bat yet, and none of them have exactly locked down a regular job with their performance at the plate. Neither prospect is on the 40-man roster, which is an obstacle to their promotion all the way to the majors this year, but if the Jays decide they need to make a splash over the summer, remaking the entire left side of their infield with two potential stars who could be in town through 2025 or so might seem very tempting.

Nick Senzel, Reds: Among the list of players many people thought would be in the majors already, Senzel is standing awkwardly alone, like the last guy in the green room at the NFL Draft (timely reference? Check!) RotoWire's No. 7 fantasy prospect, the 22-year-old hasn't done much to force the Reds into promoting him, putting together a .231/.315/.338 slash line in 16 games for Triple-A Louisville, but while his strikeout rate has risen a bit it's hardly out of control at 23.3 percent. Eugenio Suarez is also about to come off the DL, closing Senzel's apparent window to make a quick jump into the starting job at the hot corner. On the other hand, Cincinnati's season is already on the rocks. They've fired their manager, which is what having a record worse than the Marlins will get you, and nobody on the roster has come out of the gates smelling like roses. Jose Peraza, in particular, is once again looking like a player better suited to a utility role than a starting spot, and the team would seem to have little to lose by putting Peraza on the bench, shifting Suarez back to shortstop and calling up Senzel.

Michael Kopech, White Sox: Between the end of 2017 and the beginning of this season, Kopech has now made seven starts with Triple-A Charlotte. He's been alright, I guess, if you like pitchers with an 11.5 K/9 and a 2.50 ERA. He's also got a 3.0 BB/9, which is a huge improvement on his control at lower levels and is arguably the last piece of the puzzle for the potential future ace. The White Sox also have plenty of vacancies in their big-league rotation. Reynaldo Lopez and Lucas Giolito aren't going anywhere, and Carlos Rodon should be back in a month or so to reclaim a job, but that that still leaves two big holes currently being plugged by the likes of James Shields (in the last year of his contract) and Carson Fulmer (doing nothing to prove he has a future outside of the bullpen), plus retreads like Chris Volstad and Miguel Gonzalez. When the front office decides it's time to start Kopech's service clock, those guys won't so much be obstacles as turnstiles. Of all the pitching prospects who could realistically seize a rotation job later in 2018, the right-hander – who turns 21 on Monday – has the highest pure upside, and no I haven't forgotten about Forrest Whitley or Walker Buehler.

Austin Riley, Braves: No. 18 on RotoWire's Top 400, Riley could very easily not see the majors at all this season. He's not on the 40, he's only 21, and he's only at Double-A Mississippi. The Braves are also going to give Jose Bautista a try as their starting third baseman in an attempt to provide Freddie Freeman with some help in the middle of the order, potentially blocking Riley for the rest of the year if the veteran works out. That's a big if, though. Putting aside any discussion of what a defensive adventure he could be after spending a lot of years as a barely adequate right fielder, Bautista looked pretty done last year, with his .674 OPS being the lowest of his career. Yes, even lower than his pre-Joey Bats days with the Pirates. In fact, Riley might actually be the better option to hit behind Freeman and keep opposing pitchers from walking him quite so much. The kid's absolutely crushing Southern League pitching, slashing .352/.410/.718 through 20 games, and 15 of his 25 hits have gone for extra bases (eight doubles, three triples, four homers). He'll probably get promoted to Triple-A Gwinnett to take Bautista's place once Atlanta is ready to begin that bold experiment, and if he doesn't slow down in the International League – and Bautista's bat-flipping act turns into a flop – Riley could join Acuna and Ozzie Albies is a very young, and scarily talented, Braves lineup for the stretch run.

Willy Adames, Rays: So far this season, the Rays have resisted the temptation to promote any of their Triple-A prospects despite a rash of injuries on the big-league roster, which is pretty much par for the course with the organization. Nobody drags their feet on starting a service-time clock like the Rays. At some point, though, the front office will reluctantly decide that they've saved enough hypothetical future money to call somebody up, and that somebody will almost certainly be Adames. RotoWire's No. 21 prospect has a .355/.455/.581 slash line through 18 games for Triple-A Durham and doesn't really have anything left to prove in the minors. He lacks the pure upside of the prospects listed above, which maybe makes him a better stash in AL-only and deep mixed formats than shallow mixers, but a middle infielder who can provide at least modest production in all five of the usual roto categories can find a home on most fantasy rosters.

Willie Calhoun, Rangers: I have to admit, I've always been a bit skeptical of Calhoun's ultimate fantasy value. We have him listed at No. 41 in the prospect rankings, but there are plenty of guys below him I'd rather have on my keeper and dynasty rosters. Players who can hit, but don't have defensive homes, usually take longer to stick in the majors, and frankly the Rangers already have a "professional hitter" like that in Shin-Soo Choo, which is probably why they didn't have room on the 25-man roster for Calhoun to begin the season. His reaction to heading back to Triple-A Round Rock also hasn't done him any favors, as he's sulked his way to a .243/.317/.405 slash line after having little difficulty at the level last year. His bat will come around, and with the Rangers bringing up the rear in the AL West, players like Choo could soon be heading out of town to open up a spot for Calhoun in the left field/DH mix. Just don't be surprised if there are further fits and starts in his progress before he finally locks down a regular spot in the Texas lineup.

Garrett Hampson, Rockies: Now we're getting down to some names who maybe weren't on people's re-draft radar to begin 2018, which means names more likely to be available in competitive leagues. Hampson is No. 74 in the prospect rankings, but he's got plenty of helium after a .314/.407/.457 start at Double-A Hartford that includes a perfect 12-for-12 performance on the basepaths, and Hartford is a destination that plenty of previous Rockies prospects have struggled to conquer. More impressive than his slash line is his 11:6 BB:K through 19 games, and the 23-year-old already seems ready for a promotion. Could that promotion be all the way to the majors, though? The wild card here is DJ LeMahieu's expiring contract. The Rockies' second baseman and leadoff hitter is a free agent in the offseason and could be dealt away if the club falls out of serious playoff contention, in which case calling up another second baseman with leadoff skills could be the logical next step, especially if they decide they'd rather let Brendan Rodgers continue developing as a shortstop.

Freddy Peralta, Brewers: Peralta was something of a pop-up prospect in 2017, emerging from relative obscurity to dominate at Double-A Biloxi in 63.2 innings. The 21-year-old has been even better in a small sample so far at Triple-A Colorado Springs, posting a 1.29 ERA and 27:9 K:BB in 21 innings while pitching in one of the toughest environments for pitchers in the minors. He's still only No. 143 in the prospects rankings, but he's on the 40-man roster for the Brewers and given his proximity to the majors, a callup this year seems inevitable, even if it's only on a short-term basis. His walk rate is a concern, and being an under-sized right-hander will cause the usual crowd to insist he's a future reliever until he proves otherwise, but even if Milwaukee brings him up to fill a bullpen role he could provide value in deeper leagues as a Chris Devenski type of guy, and his ceiling is higher than that if he gets a chance to start.

Oscar Mercado, Cardinals: Look, it happens every year, so you know it's coming. At some point in 2018, St. Louis will bring up a player you've barely heard of and he'll tear the cover off the ball. That player could still be Harrison Bader, but if it's not, it should be Mercado. (Unless it's Adolis Garcia.) The 23-year-old sits at No. 147 on RotoWire's Top 400, but Mercado's hinted at big-time skill growth to begin the season, reducing his strikeout rate and increasing his walk rate at Triple-A Memphis compared to his Double-A performance while posting a .308/.384/.477 slash line. A slow-developing bat actually isn't a surprise considering his career path – he was a catcher when drafted out of high school, got moved out to shortstop for a couple of years, and has now found a defensive home in center field. He's got good speed and a little power, and if the Cards have a hole to fill in their outfield, he'll be the next man up.

Fernando Romero, Twins: RotoWire's prospect maven James Anderson and I rarely have radical disagreements on prospects, but Romero might be one of the exceptions. Sitting way down at No. 275 in the rankings, James sees him as a likely future middle-relief arm. I'm more optimistic about his chances of sticking in the rotation, and the 23-year-old is making me look smart through the extremely early part of this season, racking up a 1.69 ERA and 17:7 K:BB through his first 16 Triple-A innings. More importantly for his 2018 fantasy prospects, the Twins' offseason attempts to bolster their rotation haven't exactly been working out. Lance Lynn's abbreviated spring and weather-ravaged schedule have led to some dreadful numbers while Jake Odorizzi hasn't been a whole lot better, and holdovers Kyle Gibson and Phil Hughes have been erratic at best. Romero doesn't have Jose Berrios' upside, but if some of the veterans fail to turn things around or turn out to be nursing injuries, his three solid pitches could help staunch the bleeding for a club expecting to be in the playoff hunt.