The truly elite prospects are few and far between. For prospects of the mortal variety, standing in the prospect rankings can ebb and flow. Sometimes a player advances further and more quickly than anyone expected, or a former organizational darling struggles unexpectedly.
As 2019 closes and many teams start to think more publicly about 2020, there are, as usual, a number of prospects who have put themselves on the radar for the 2020 season. Most won't become Pete Alonso, who went from an interesting High-A slugger to Triple-A terror in 2018 and is going for the 50-homer mark in 2019. But many of these players will contribute to MLB teams at some point in 2020.
I've tried to find one interesting player of this type for each team. I did not cheat and go with any of the obvious elite talents. If I told you "Casey Mize and Luis Robert might be good players in 2020," the proper response would be "No duh, Szymborski."
Arizona Diamondbacks: 1B Seth Beer
If you have only one trick, hitting is a pretty good one to have. Beer doesn't excite prospect-watchers, given that he isn't loaded with tools besides that one. Christian Walker has had a nice year, but Beer has more offensive upside, and Arizona will be interested in showing off a player it got in the Greinke trade.
Atlanta Braves: C Alex Jackson
This is a revival of sorts, with Jackson almost being forgotten as a prospect after a series of injuries. He has continued to improve as a catcher, and his power has largely gotten back to what it was in his days on the Mariners' prospect lists. Jackson is not a top prospect, but he's interesting again, and it's in Atlanta's interest to see what it has in Jackson before catching prospect Shea Langeliers (a 2019 first-round pick) starts pushing up from below.
Baltimore Orioles: RHP Dean Kremer
The Orioles are so desperate for pitching that simply being in Norfolk and having a working arm would likely be enough to earn a pitcher an audition at some point in 2020. Don't be fooled by Kremer's ugly Triple-A ERA (8.84 in four starts). He is avoiding walking batters or allowing home runs just as well as he did at the lower levels, and not giving up homers has become especially crucial in today's environment.
Boston Red Sox: 3B Bobby Dalbec
Rafael Devers is of course a gigantic roadblock for any Red Sox prospect at third base, but Dalbec's power has continued to play in the high minors. At some point, the Red Sox will probably stop signing Mitch Moreland every offseason, which would open up a corner.
Chicago Cubs: RHP Cory Abbott
Abbott doesn't have a high ceiling, but all he did this year was get results in the Double-A Southern League with a fairly deep repertoire marred only by a lack of flash. He gets as much out of an average fastball as he can, thanks to good control and a fun cutter, and the Cubs have done well with pitchers of this type in the past (see: Hendricks, Kyle).
Chicago White Sox: C/1B Zack Collins
The team hasn't shown a great deal of interest in finding Collins at-bats in the majors after nine rather indifferent starts, but there are no 2020 roadblocks at first base and DH until/unless the team re-signs Jose Abreu beyond this season. Collins probably can't stick at catcher, but he could contribute enough offensively to stick at first.
Cincinnati Reds: CF Stuart Fairchild
Fairchild isn't on the top prospect radar, and his name sounds more like that of a billionaire financier on a soap opera than a baseball player, but the Reds can always use another outfielder who will draw a walk and play center. His time in the majors might depend on the Reds getting Nick Senzel back into the infield, or else Fairchild might not have enough room to pop up in late 2020.
Cleveland Indians: OF Daniel Johnson
Yadda yadda yadda Triple-A offensive boom etc., but the lesser name who came over in the Yan Gomes trade has a better than .850 OPS at both Double- and Triple-A in 2019, and the Indians are always searching for outfield talent (or at least they should be, since such behavior wasn't always present last winter).
Colorado Rockies: LHP Ben Bowden
Perhaps instead of paying for any veteran reliever who was good in 2016, the Rockies ought to find their own relief talent? Bowden was waylaid by back issues, but he throws hard, changes speeds and doesn't allow a billion homers, which is nice in Colorado.
Detroit Tigers: RHP Alex Faedo
For a first-round pick, it sure seems like Faedo was forgotten quickly. Disappointing velocity or not, he has done as much as he can do in Double-A, and given his lowered prospect status, the Tigers probably won't be as cautious with him as with Casey Mize or Matt Manning.
Houston Astros: RHP Brandon Bielak
Houston has cleared away some of the pitchers above Bielak in the pecking order in recent trades, and there will likely be some innings to be found for Bielak if he continues to find success with his ordinary stuff. Allowing only a home run per game in the Pacific Coast League is easier said than done in 2019, given that the Triple-A leagues adopted the MLB baseball.
Kansas City Royals: RHP Jackson Kowar
The Royals had a lot of disappointment in the minors this year (Nick Pratto, MJ Melendez, Seuly Matias), and a lot of their successes were expected. One of the exceptions to underachievers among their collection of second-tier prospects was Kowar, a fastball/curve/change pitcher whose velocity comfortably sits in the mid-90s and who has decent control. He can stick as a starter, but he could pop up in a very thin Kansas City bullpen at some point in 2020.
Los Angeles Angels: UT Jose Rojas
He's old for a prospect, but one has to remember that he was 23 years old when he was drafted out of college. All Rojas has done in the minors is hit, and while he has no doubt taken advantage of the PCL's high-octane offensive environment this year, someone who can fake second base and hits .304/.381/.554 in Double-A (as he did in 2018) is a player to look at. Maybe he's Dan Uggla: The Next Generation. That would be a disappointing TV series but a useful player to have.
Los Angeles Dodgers: RHP Josiah Gray
I guess I can't use Gavin Lux at this point, can I? I submit instead Josiah Gray, a hard-throwing Dodgers hurler who might have been the most valuable player to change teams in the gigantic Dodgers/Reds Puig/Wood trade last winter. In Gray's first full professional season, he tore up three levels and showed impressive command for a prospect who can reach 97 mph with his fastball.
Miami Marlins: 1B Lewin Diaz
After 2018 was ruined for Diaz by a broken thumb, he struck a decidedly different note in 2019, hitting 27 homers between the Florida State and Southern Leagues. Picked up in the Sergio Romo trade, Diaz has little competition ahead of him on the Marlins' depth chart.
Milwaukee Brewers: RHP Drew Rasmussen
Rasmussen has survived two Tommy John surgeries with his fastball intact, and though he has been starting, injuries to the big league bullpen make that likely his best ticket for MLB employment in 2020. It would be nice if Rasmussen shed a walk per nine, but getting through three minor league levels in his professional debut (and first fully healthy year since 2015!) is an impressive feat.
Minnesota Twins: RHP Jhoan Duran
Although 2020 might be a bit optimistic for Duran, his Double-A debut was better than his 4.86 ERA indicated, and his splitter/fastball thing keeps hit balls out of the stands. I think he could blow through the upper minors very quickly.
New York Mets: LHP David Peterson
Peterson won't impress with stuff, and his fastball seems curiously slow for a big guy who looks like he wandered in from a Game of Thrones battle scene, but he keeps the ball down and doesn't suffer from massive platoon splits, the Achilles' heel of the ordinary minor league lefty. The Mets should have an open spot or two at the back of the rotation, and there isn't a lot of competition in the upper minors. Plus, the Mets haven't misdiagnosed any Peterson injuries yet!
New York Yankees: RHP Deivi Garcia
Garcia wowed the public at the All-Star Futures game in Cleveland and probably could have mowed down several more batters based on the fastballs he was throwing in warm-ups with shockingly little effort. Whether he ends up in the bullpen or the rotation, I'll bet on a guy with two pitches as nasty as his fastball and curve.
Oakland Athletics: RHP Daulton Jefferies
Want to get me excited about a pitcher in the minors? A 10:1 strikeout-to-walk ratio is a good place to start. With him further removed from Tommy John surgery, I hope Jefferies has a couple ticks more to get on his fastball. Either way, he's as good a control pitcher as there is in the minors right now, and the A's don't tend to be biased against those guys.
Philadelphia Phillies: RHP Spencer Howard
The Phillies could still make the playoffs, but it won't be because of any of their starting pitching after ace Aaron Nola. Howard, their 2017 second-round pick, has quickly ridden a mid-to-upper-90s fastball and a couple solid breaking pitches through the lower minors. With his control vastly improving, he could sneak into some innings in Philadelphia in 2020 and contribute.
Pittsburgh Pirates: SS Oneil Cruz
A 6-foot-6 shortstop is an odd sight, but Cruz has yet to outgrow the position. Importantly, he has kept hitting in the minors, combining for a .298/.354/.478 line for High-A Bradenton and Double-A Altoona in 2019. At this point, Cole Tucker won't block Cruz.
St. Louis Cardinals: OF Dylan Carlson
Perhaps the best comparison for Pete Alonso in his situation a year ago -- and no, before you go there, I'm not projecting Carlson to hit 50 homers next year -- Carlson has pulled himself back from first-round bust territory this year, crushing pitchers in Double-A Springfield before continuing with nine extra-base hits in 17 games for Memphis. Carlson won't get a September call-up, but with him turning just 21 years old this fall, the Cards ought to do better for him than the casual disinterest they've already shown Tyler O'Neill.
San Diego Padres: C/1B Austin Allen
Hitting .330/.379/.663 in the PCL was enough to get Allen some time in San Diego with Francisco Mejia injured. The problem for Allen is that he's extremely unlikely to be able to supplant both Mejia and Austin Hedges and stick at catcher for the Padres. Eric Hosmer might not be very good, but he's signed for a very, very long time. I think Allen will hit in the majors, but it might need to be for another organization.
San Francisco Giants: SS Mauricio Dubon
Dubon was mostly forgotten since heading to Milwaukee in the Tyler Thornburg trade, and the Brewers didn't think enough of him to give him a shot at supplanting the eternally underwhelming Orlando Arcia at short. But after hitting .302/.345/.477 and with the Giants' lineup full of holes, Dubon will get a chance to stick in 2020.
Seattle Mariners: CF Jake Fraley
If I had my choice, Fraley would start the rest of the season in Seattle. One of the quicker developing players I can remember, Fraley wasn't expected to be a big hitter when he was drafted in the second round in 2016. He was thought of as more of a traditional center field type. After a .347/.415/.547 line out of nowhere for High-A Charlotte in 2018, Fraley has hit .298/.365/.545 at two high minors stops in 2019.
Tampa Bay Rays: UT Jake Cronenworth
OK, there are a lot of tales of Triple-A hitters having a big year out of nowhere thanks to the new ball, but Cronenworth's .962 OPS breakout has come on the back of his hitting just 10 homers. Cronenworth's plate discipline is MLB-quality, and he has played all four infield positions in the minors. The Rays have even let him pitch a tiny bit this year, as he did in college. Cronenworth is in one of the best organizations for a Swiss Army ballplayer.
Solak was one of my favorite pickups this season by any team, with the Rangers quietly acquiring him from the Rays for righty Peter Fairbanks back in July. Solak has followed an .834 OPS in 2018 with an .894 OPS in 2019, and he has continued to hit since his call-up. The Rangers ought to give Solak every opportunity to make his case for starting in 2020.
Toronto Blue Jays: RHP Thomas Hatch
Picked up from the Cubs this summer for journeyman David Phelps, Hatch finds himself in a good position going forward, with precisely none of Toronto's rotation spots set in stone for 2020. Held back thanks to a few too many walks and some brutal platoon splits (minor league lefty batters hit .276/.385/.482 off Hatch in 2018), Hatch at least made progress with his control. With better control, the hope is that his changeup proves to be a good weapon against lefties. He'll get a chance with the Jays in 2020, in all likelihood.
Washington Nationals: RHP Jhonatan German
James Bourque tends to get the attention among Nats relief prospects, but with a solid fastball of his own and better control than Bourque, German ought to advance through the upper minors very quickly in 2020. At some point, the Nats are going to break their awful habit of giving up on interesting young relievers and then watching them succeed elsewhere -- Felipe Vazquez, Blake Treinen, Trevor Gott, Austin Adams and so on.