Last week's 5 biggest fantasy surprises: Will Jazz Chisholm Jr. continue his breakout?

Miami Marlins infielder Jazz Chisholm Jr. came into the 2022 fantasy baseball season with a lot of potential. He hit for decent power and stole a fair amount of bags during his first full season in MLB. He did that at a thin fantasy position, making Chisholm an even more desirable target in fantasy leagues.

That skill set, while tantalizing, came with risks. As a result, Chisholm ranked as the 82nd best player heading into the 2022 season.

Fantasy managers who took the plunge on Chisholm look real smart right now. Chisholm has outperformed his preseason ranking and is currently 25th in standard Yahoo fantasy leagues.

Should fantasy managers expect that surge to continue, or is Chisholm the type of player who should be sold high as the trade deadline approaches?

Ranks are based on standard Yahoo fantasy leagues

Jazz Chisholm Jr., Miami Marlins 2B, SS

Fantasy rank over the last seven days: 5

Season-long fantasy rank: 25

Chisholm appears to have made a conscious decision to tap into his power more in 2022. His flyball rate is up nearly 10 percent and his pull rate is up over 10 percent compared to last season. That adjustment would help most batters club more home runs, but Chisholm is really doing himself a favor by barreling the ball 17.2 percent of the time, an extreme rate, and posting a 46.9 percent hard-hit rate.

That barrel rate should regress as the season goes on but is unlikely to drop all the way back to the 9 percent barrel rate Chisholm posted in 2021. He's shown enough at the plate to say he's an improved hitter and his production is not a result of luck.

With that said, there is one reason for concern. Despite the improvements, Chisholm's swinging-strike rate is up to a career-high 13.4 percent. He's swinging and missing more often, which should lead to a higher strikeout rate and lower batting average. Chisholm is hitting .246 — league average is .242; a drop would make Chisholm a liability for some fantasy teams.

Chisholm still does plenty right to buy the breakout, however. The power surge looks real and he still has an elite sprint speed, a sign the stolen bases will continue. There could be some batting average regression, but not enough to completely tank Chisholm's value.

Fantasy managers worried about that drop could try to acquire a player with a strong batting average — maybe a Michael Brantley? Nonetheless, it's probably worth holding onto Chisholm.

Cody Bellinger, Los Angeles Dodgers OF

Fantasy rank over the last seven days: 542

Season-long fantasy rank: 288

What in the world happened to Cody Bellinger?

After a strong start to his career, Bellinger has delivered three straight years of disappointing-to-awful production. Early returns in 2022 suggest another poor season could be on the way.

Digging deeper into Bellinger's numbers reveals ... a mixed bag. Bellinger's strikeout rate sits at a career-high 29.6 percent. That figure explains his poor .207 batting average and doesn't offer much hope that Bellinger will return to the days where he hit .260.

However, Bellinger's swinging strike rate is down to 11.4 percent, better than his first two seasons in the league, when Bellinger hit .263. So, why is Bellinger's average so low? A passive approach at the plate is probably to blame. Bellinger is swinging less at pitches in the zone, allowing pitchers to get ahead in the count.

Being more aggressive should help. Bellinger is making more contact compared to last year and he appears to have figured out his struggles against fastballs. The pitch gave him major issues in 2021 when he hit .194 against four-seamers. Bellinger is up to hitting .261 against them in 2022.

Changes need to be made, but there's evidence Bellinger can perform better at the plate. Getting back to a .260 batting average feels like a lot to ask, however, so fantasy managers need to figure out whether Bellinger has enough value to remain on rosters if he's hitting only .230.

Jeffrey Springs, Tampa Bay Rays SP

Fantasy rank over the last seven days: 47

Season-long fantasy rank: 48

Sigh. Another year, another previously unknown pitcher dominating with the Tampa Bay Rays.

We already coveredDrew Rasmussen — who continues to put up strong numbers — in May. Now, Jeffrey Springs deserves attention. Over his last seven games (all starts) Springs has a 1.72 ERA with 36 strikeouts in 36 2/3 innings.

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Springs has spent the vast majority of his career pitching out of the bullpen, so it's tough to fully evaluate how his stuff will continue to play in the rotation. However, he is doing some encouraging things thus far. Both his changeup and slider look strong. The changeup has always been a solid option for Springs, and he's using the pitch more in 2022.

The slider looks like a different pitch, though. Springs is throwing it harder and it's not dropping as much. Think of it as a slow cutter, but with more horizontal movement than most cutters.

Those improvements are enough to make Springs an intriguing pickup in most leagues. Things won't be this good all season, obviously. Springs fastball isn't as effective now that he is throwing longer stints, and the Rays are usually cautious to push pitchers deep into games. His ratios should continue to be solid though, especially if the gains on the changeup and slider are real.

Ke'Bryan Hayes, Pittsburgh Pirates 3B

Fantasy rank over the last seven days: 697

Season-long fantasy rank: 197

Ke'Bryan Hayes was never going to re-create the sizzling numbers he produced as a rookie, but that season seemed to signal the Pittsburgh Pirates had a future superstar on their hands. That hasn't happened just yet.

Hayes, 25, hasn't been bad this season, but his numbers haven't stood out either. Hayes is hitting .277/.359/.374 through 55 games. The lack of power remains a major concern after he slugged .373 in 2021.

Everything else about Hayes' game looks extremely promising. His Statcast page is full of red in some key areas. His hard-hit rate ranks in the 90th percentile, his average exit velocity sits in the 89th percentile and his max exit velocity falls into the 87th percentile. All those signs indicate Hayes should be a high-average hitter with good power.

Why hasn't that happened?

Hayes' home park might have something to do with it. PNC Park has ranked near the bottom of the league in home run park factor the past couple of seasons. If Hayes called, say, Guaranteed Rate Field his home park, as an example, he would already have 5 home runs this season instead of just 2.

Hayes sustained a wrist injury last season, and that shouldn't be ignored here. But the red numbers on his Statcast page suggest that injury hasn't held him back much. While Hayes' average of 93.9 mph on fly balls and line drives ranks 98th in MLB, that figure puts him near Tyler O'Neill and Mookie Betts, both players who can hit for above-average power.

Nearly everything in his profile suggests Hayes should be a much better hitter. His poor power numbers are tough to explain. He will likely be held back by his home park and the pieces around him, but there's still plenty of evidence he can go on a tear and become a fantasy star.

Lucas Giolito, Chicago White Sox SP

Fantasy rank over the last seven days: 573

Season-long fantasy rank: 413

It's been a disappointing start for Lucas Giolito. He was a dark horse candidate to win a Cy Young award in 2022 but has a 3.88 ERA and 1.44 WHIP through his first 10 starts.

It's clear something is off with Giolito thus far. His walk rate is up and his changeup has been knocked around much more than usual. Prior to 2022, the pitch was one of the best changeups in the majors. Giolito has also allowed an extremely high 1.86 home run per nine rate and a .352 BABIP.

The good thing is ... those last two numbers should regress. Even during Giolito's 2018 season, when he was literally the worst pitcher in baseball, he had a lower home run rate and BABIP. It's also likely that his changeup returns to form. It would be pretty unusual if he suddenly lost the ability to throw his best pitch.

The walk rate concerns can't be fully dismissed, as Giolito has had trouble with command throughout his career. It's worth noting he has posted good walk rates in two of the past three seasons, however.

Given the extreme nature of his issues in 2022, Giolito could be dealing with mechanical issues on the mound. A player of his caliber shouldn't suddenly lose his ability after three excellent seasons.

Giolito has shown the ability to make adjustments in the past, providing hope he can do it again in 2022. Better days are ahead.