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One of the most pressing questions about Major League Baseball's upcoming season is how young players will develop after last year's unusual and potentially disruptive campaign. The lack of a minor-league season because of COVID-19 concerns left prospects in an awkward position: most had to train on their own, while those who were able to attend their teams' alternate sites were exposed to a different kind of training regiment (a few were even permitted to play in the majors before they would have otherwise, seemingly in an attempt to get them valuable reps against actual opponents).

The rank-and-file prospects weren't the only ones impacted. Some of the biggest names in the scouting world, Jo Adell and Casey Mize included, had (understandably) poor or otherwise disappointing rookie seasons. Still, while we have empathy for any player who found it hard to perform at their best last year, the world of baseball writing and analysis demands that we dissect their lackluster seasons and divine What It Means for them heading forward. Below, you'll find said analysis for four notable youngsters who struggled in 2020. (Note: the players are presented in alphabetical order.)

1. Jo Adell, OF, Los Angeles Angels

What was supposed to happen: Adell gives the Angels another dynamic talent, and wins the Rookie of the Year Award en route to a playoff berth.

What did happen: Adell hit .161/.212/.266 with 48 more strikeouts than walks in 38 games. (He didn't win any hardware and the Angels didn't make the postseason.)

What's next: Adell seems certain to open the year in the minors. The Angels have spent the winter restocking their outfield depth chart by trading for Dexter Fowler and signing non-roster types like Juan Lagares, Scott Schebler, and Jon Jay. Those players are bandaids, not long-term solutions, but they should enable the Angels to play it slower with Adell than they had to last season.

Between now and that indeterminable date, Adell has a lot to work on. He struggled with pitch recognition, fishing after too many pitches below the zone and even looking uncomfortable on takes. He didn't show good bat-to-ball skills, either, and his 64.6 in-zone contact rate ranked 467th out of 475 players with at least 25 trips to the plate. Predictably, Adell tinkered with his swing in an attempt to find something that worked; nothing took: his .505 OPS in August was superior to his .437 OPS in September.

For as poor as the results were, Adell still showed the explosive bat and foot speed that made him a top prospect in the first place. He didn't connect often enough, but when he did, his average exit velocity (90.6 mph) ranked in the 78th percentile. His sprint speed, meanwhile, was in the 98th percentile, according to Statcast. Those innate traits are one reason to hold out hope. Another is that Adell didn't spend much time in the upper minors before last year. Coming into this season, he'll have 385 total plate appearances at the Double- and Triple-A levels; Fernando Tatis Jr. skipped Triple-A and debuted in the majors when he was 20 years old, and he had 459 plate appearances at Double-A.

It's reasonable to have more reservations about Adell now than this time last year — a front office source even wondered to CBS Sports if the Angels would move him over the winter -- but his ceiling remains lofty. The Angels can only hope that additional time in the minors positions Adell to handle big-league pitching, and thereby raises his floor.

2. Carter Kieboom, 3B, Washington Nationals

What was supposed to happen: Kieboom replaces Anthony Rendon at the hot corner without issue, helping the Nationals in their efforts to repeat.

What did happen: Kieboom hit .202/.344/.212 and spent time at the alternate site and on the injured list with a wrist contusion. (The Nationals did not repeat.)

What's next: The Nationals were a trendy potential landing spot for someone veteran third baseman this winter, be it DJ LeMahieu, Kris Bryant, Justin Turner or whomever else. None of those individuals will begin the season residing in the District of Columbia. Rather, the Nationals will again give Kieboom a chance to claim the hot corner as his own. The biggest difference between this and last year is that the"non-threatening veteran Plan B" role will be filled by Josh Harrison instead of Asdrubal Cabrera.

That may be the biggest difference, but it isn't the only one. Kieboom, for his part, added another 122 ineffectual plate appearances on top of the 43 he racked up in 2019. His career line is now .181/.309/.232 with more than twice as many strikeouts as walks and just three extra-base hits in 165 plate appearances. His 47 OPS+ in that span puts him in company with a bunch of no-hit backup catchers; end-of-line veterans; and fellow disappointing youth, like Lewis Brinson and Isan Diaz.

Is there any reason for hope -- other than noting it's only 165 plate appearances? Sure. Kieboom won't turn 24 until September, and he has a track record of hitting. (He's a career .303/.409/.493 in 109 Triple-A games.) He also has a good handle on the strike zone, and his strikeout and walk rates both went in the right direction last season. It would almost be fair to wonder if he's too patient: he upped his swing percentage to 44.4 percent last year -- a nine-percentage-point increase over his 2019 cameo -- and that's still a touch below the league-average mark. 

Kieboom's utter lack of power output is concerning, and he'll need to start striking the ball with greater authority if he's going to live up to his middle-of-the-order upside.

3. Gavin Lux, INF, Los Angeles Dodgers

What was supposed to happen: Lux hits his way into the Dodgers most-days starting nine, and helps them get over the hump in October.

What did happen: Lux hit .175/.246/.349 and appeared in only 19 games, not including the one playoff game he appeared in for the title-winning Dodgers.

What's next: Lux had a year to forget (at least at a personal performance level): he didn't make his season debut until late August because of a combination of the Dodgers' depth and his own offensive and defensive woes. He did receive some semblance of steady burn in September, and even had a three-hit, two-homer game against the Diamondbacks. From that point on, he went 4 for 31 with one walk, nine strikeouts, and just one other extra-base hit. Woof.

More so than anyone else in this article, Lux has shown signs of being ready to contribute. His career numbers aren't pretty, but he's walked in nearly nine percent of his plate appearances and he has a .167 isolated slugging. That's a good base from which to build upon at the plate. The problems for him have been strikeouts (nearly 30 percent) and a single allergy, as he had just six one-base hits in 2020 (versus five extra-base hits).

Assuming that Lux's non-home-run balls in play start finding holes, he should be fine. The question, then, is where do the Dodgers station him on the diamond? Second base is one option, but he's had enough throwing issues that he might end up in left field. Either way, Lux seems he should be fine entering his age-23 season.

4. Casey Mize, RHP, Detroit Tigers

What was supposed to happen: Mize joins the big-league rotation early on, and pitches like an above-average starter with contact manager qualities.  

What did happen: Mize joined the rotation early on, and pitched like a below-average starter (6.99 ERA, 2.00 strikeout-to-walk ratio) without contact manager qualities. 

What's next: Mize may also begin the year in the minors, depending on if the Tigers implement a six-pitcher rotation and how they decide who gets those slots. At minimum, he doesn't appear to be a lock for a club that hasn't won more than 40 percent of its game since 2015. It's not, as the kids say, what you want.

Mize was supposed to be able to limit free passes and hard contact with well-located fastballs, cutters, and splitters. Alas, he didn't do any of that. He ranked in the 45th percentile in exit velocity and threw just 60 percent strikes (league-average is around 63 percent). He gave up more than two home runs and four walks per nine innings. Oh, and opponents hit .313 with a .469 slugging percentage against his signature splitter.

Mize told FanGraphs' David Laurila in January that he's working on his "vertically" by implementing more high four-seam fastballs. That's not the worst idea; his four-seamer was his best pitch statistically, and the strike zone is taller than the plate is wide. Besides, having another look to throw at hitters is never a bad idea.

It will be interesting to see how patient the Tigers are with Mize if he struggles over a more prolonged period. There's no rush competitively to move him to the bullpen, but Mize's past injury issues could force them to weigh it sooner than they might otherwise. For now, here's hoping that Mize -- along with the other youngsters reference here -- can turn their careers around with solid sophomore efforts.