While many of the established players who struggled during the truncated 2020 season quickly rebounded when MLB returned to a typical schedule, a number of stars were not able to get back on track, creating more uncertainty entering the 2022 campaign.

The players below fall into the latter group. Although these veterans have had their share of success at baseball’s highest level in the past, each has a lot to prove in the upcoming season.

Cody Bellinger, OF, Dodgers
No one on this list has had a steeper fall than Bellinger, who won the 2019 NL MVP Award with a .305 average, 47 homers and a 1.035 OPS, only to hit .195 with 22 homers and a .642 OPS in 2020 and 2021. Bellinger feasted on fastballs during his MVP campaign, but he’s looked overmatched against the hard stuff in the past two years, recording the lowest average (.184) and the ninth-lowest slugging percentage (.339) in the Majors on fastballs (min. 250 PAs ending on fastballs). Manager Dave Roberts said last August that he thought Bellinger was still dealing with the aftereffects of the right shoulder surgery he underwent to repair a dislocation after 2020. The left-handed slugger also had to battle through a hairline fracture in his left fibula, left hamstring tightness and a fractured left rib last season. With a clean bill of health entering the 2022 season, the 26-year-old is a prime candidate to bounce back.

Madison Bumgarner, LHP, D-backs
While Bumgarner’s velocity and strikeout rate both ticked upward in his second season with the D-backs, he still finished with the second-worst ERA (4.67) of his career. The worst? His 6.48 mark the year before. Among pitchers who have made at least 30 starts since the beginning of 2020, only four pitchers have posted a higher FIP than the left-hander’s 5.20. Bumgarner once seemed to be on a Hall of Fame trajectory; according to Baseball-Reference, Steve Carlton was his most similar comp through the age of 27, and that didn’t even factor in Bumgarner’s postseason success. But in his age-32 season, he’ll be trying to prove he can still be an average big league starter.

Patrick Corbin, LHP, Nationals
The first season of Corbin’s six-year, $140 million deal with the Nationals couldn’t have gone much better -- he posted a 3.25 ERA with 238 strikeouts over 202 innings and the team won the World Series. However, the left-hander took a step backward in 2020 and was unable to rebound last season, leading MLB in earned runs (111) and the NL in homers allowed (37). Now 32, he still has three years left on his contract as Washington tries to rebuild.

Keston Hiura, 1B, Brewers
The ninth overall pick in the 2017 Draft, Hiura appeared to be a foundational piece for Milwaukee when he hit .303/.368/.570 over 348 plate appearances as a rookie in 2019, counteracting a lofty strikeout rate (30.8%) with a 97th-percentile hard-hit rate (50%). However, over the past two seasons, Hiura’s hard-hit rate has slipped to 40.3% while his K-rate has spiked to 36.6%, contributing to a .192/.279/.362 slash line. He’s also a man without a position after losing his second-base job to free-agent signing Kolten Wong and his first-base job to trade acquisition Rowdy Tellez in the span of five months last year, though the addition of the designated hitter in the NL could open the door for him to earn consistent playing time in 2022. Hiura's still just 25, so he has time to figure things out, but the Brewers have already shown they aren’t above sending him to the bench or the Minors if he isn’t producing.

Francisco Lindor, SS, Mets
Lindor remains one of the premier defensive shortstops in the game, but he’s been close to league average with a 102 OPS+ over the past two years. The Mets are counting on him to be much better than that after signing him to a 10-year, $341 million extension through 2031. Lindor did have increased offensive success in the second half last season, recording an .813 OPS (.698 first-half OPS), so it’s possible he just needed some time to adjust to playing in New York.

Chris Paddack, RHP, Padres
Paddack was the Padres' other prized rookie in 2019, joining Fernando Tatis Jr. on the Opening Day roster despite having no experience above Double-A at the time. He ended the year with a 3.33 ERA and a 4.94 K/BB ratio over 140 2/3 innings. He hasn’t been able to build on that success, though, recording a 4.95 ERA in the past two seasons despite a strong 4.62 K/BB ratio. While Paddack seemed to find a reliable third offering in his curveball last year, his four-seamer was hit hard again -- opponents have slugged .575 against the 26-year-old’s heater since the beginning of 2020. It’s something he’ll likely need to figure out to find his way back into San Diego’s rotation.

Eugenio Suárez, 3B, Reds
Suárez leads the Majors with 129 homers since the outset of 2018, but after producing a 133 OPS+ over 2018-19, the strikeout-prone slugger put up a 100 OPS+ in 2020 and an 80 OPS+ in 2021. It’s possible Suárez’s defensive struggles after Cincinnati moved him to shortstop last spring contributed to his slow start on offense, though his plate woes continued even after the Reds shifted him back to the hot corner in May. In fact, he had a sub-.700 OPS in every month before posting a 1.268 OPS in September/October. The Reds need Suárez to provide more support for Joey Votto in the team’s lineup, especially after Nick Castellanos opted out of his deal to become a free agent.

Gleyber Torres, 2B, Yankees
While Torres is only 25 years old, he’s already had an eventful career. The infielder was one of the Cubs’ top prospects before the team traded him to the Yankees in 2016’s Aroldis Chapman blockbuster. He finished third in the 2018 AL Rookie of the Year voting, then socked 38 dingers in 2019, and the Yanks installed Torres as their starting shortstop when Didi Gregorius departed as a free agent after the season. But little has gone right for Torres since -- his poor defensive performance at short caused the Yankees to shift him back to second base late in 2020, and his offensive production has cratered (12 HR, .703 OPS in 2020-21), putting his long-term future with the team in question.

Christian Yelich, OF, Brewers
Yelich won the NL MVP Award in 2018 and finished second to Bellinger the following season, hitting .327/.415/.631 with 80 homers combined in those two years. But like his Dodgers counterpart, Yelich has experienced a sharp drop in production in the past two seasons, posting a .234/.360/.392 slash line with 21 home runs over 175 games. He's also battled injuries, suffering a fractured right kneecap late in 2019 and dealing with recurring back problems. Yelich did have an 87th-percentile hard-hit rate and a 98th-percentile walk rate in 2021, but his barrel rate of 7.6% was his lowest in four years with the Brewers, as he struggled to get air under the ball (his average launch angle of 2.8 degrees was among the lowest in MLB). With seven years remaining on Yelich’s nine-year, $215 million contract, Milwaukee is counting on the 30-year-old to regain his All-Star form.