Last fantasy baseball could certainly be described as the year of the rookie. Names like Jackson Merrill, Jackson Chourio, Paul Skenes, and Shota Imanaga dominated the conversation and were all late-round draft picks that helped lead fantasy baseball teams to championships. But while these players, and many others, were consistently productive throughout the year, other rookies didn’t debut until later in the season or took a while to break through that rookie wall. Many rookies had strong second halves of the 2024 season and flew under the radar because the names above were stealing all the headlines.
This article will highlight four rookie hitters who had very strong second-half numbers that could turn into success over a full season in 2025. Each of these players goes after pick 100 in most fantasy drafts, but have at least a half-season of production to build their case as fantasy stars.
4 Second Half Rookie Hitter Breakouts
Ivan Herrera | C | St. Louis Cardinals
After a combined 24-game cup of coffee in 2022 and 2023, catcher Ivan Herrera was able to spend almost half a season with St. Louis in 2024 and the production from the young catching prospect could not have been much better. Over his games played in the second half, Herrera hit .368/.463/.579 with a 15% walk rate and an 18% strikeout rate. Working alongside Willson Contreras as a catching tandem, Herrera displayed bat skills and patience far beyond his 24 years.
Iván Herrera with his first career HR!pic.twitter.com/a7Agc13b8v
— SleeperMLB (@SleeperMLB) April 4, 2024
Of course, the best news for Herrera heading into 2025 is that Willson Contreras is likely to spend all or most of his time at first base for the St. Louis Cardinals. Herrera will only likely have competition from career minor-leaguer Pedro Pages behind the plate. Even on days when Herrera does not catch, the Cardinals might still want to find a way to keep his bat in the lineup and play him at DH over Alec Burleson, especially against left-handed pitching.
In AAA before he was called up, Herrera was hitting .280/.402/.473 with a 17% walk rate and 17% strikeout rate. His ability to get on base and pitch in potentially 12 home runs and eight steals per year makes him an extremely valuable catcher for fantasy rosters.
Colton Cowser | OF | Baltimore Orioles
The 2024 season for the Baltimore Orioles seemed like a never-ending parade of rookies coming through the clubhouse door. Colton Cowser, Heston Kjerstad, Coby Mayo, and Jackson Holliday all had various levels of success and failures as rookie hitters, but the most consistent (by far) was outfielder Colton Cowser. Cowser finished the 2024 season with a .242/.321/.447 slash line including 24 home runs in 153 games. He would finish second to Luis Gil for American League Rookie of the Year in the second-closest vote ever.
And while his entire season looks strong on paper, especially against the other more hyped Baltimore rookies, Cowser’s second half is what can give us tremendous hope for 2025. Over 64 games in the second half of the season, Cowser hit .267/.337/.477 with 12 home runs and four stolen bases. He increased his HR/FB rate and his walk rate hovered around 9.5% all season. Yes, he struck out too much at around 29%-30% all season, but even with those punchouts he was able to boost his wRC+ from 107 in the first half to 133 in the second.
Tyler Soderstrom | 1B | Athletics
Brent Rooker and Lawrence Butler stole the headlines for the Oakland Athletics last season, and now they are prized assets in any fantasy baseball draft. But much later in the draft, first baseman Tyler Soderstrom is a player who should certainly not be overlooked. After hitting just .219/.307/.404 in the first half of 2024, he exploded for .279/.340/.512 and plenty of extra-base power in the second half. What changed over that time to produce such a drastic swing in his offensive production? His ability to lay off pitches.
In this chart above from Fangraphs, the 50-game mark represents the first half and second half split for Soderstrom after topping out around 40% of pitches swung at outside the strike zone, he started being more patient and laying off bad pitches. The result was an immediate rise in his wOBA and a better approach that led to the .512 slugging percentage over that time.
Besides a full-time role as the first baseman this year, Soderstrom also gets the advantage of moving out of the cavernous Oakland Coliseum to what should be a more friendly hitting environment in Sacramento. If he slots in at the fourth or fifth spot in the lineup, this could be a 30-homer, 85-RBI season for the underrated first baseman.
Tyler Fitzgerald | SS | San Francisco Giants
Rookie shortstop Tyler Fitzgerald had a very interesting second half of 2024 compared to his first half. His first-half batting average (.278) was almost identical to the second-half (.281). His OBP before the All-Star break (.337) mirrored the second half (.333). But his slugging percentage in the second half (.519) was miles better than it was early in the season (.430). In 61 first-half games, Fitzgerald hit just two home runs. In 30 second-half games? He hit 13 plus 15 other hits that went for doubles. Take that home run surge and combine it with his 17 steals last season, and we have a fantasy diamond in the rough.
Fitzgerald’s most impressive change that led to the surge in power was his ability to start lifting the ball. He bumped up his fly ball rate from 40% in the first half to almost 47% in the second and finally started getting some luck on his side in the HR/FB department (18.6% in the second half to just under 10% in the first).
The home run surge is not completely unexpected from Fitzgerald based on his track record. He had three years in the minor leagues with at least 19 home runs. In two of those seasons, he also stole more than 20 bases, proving that he can be a late-round combination of power and speed that is every fantasy manager’s dream. Fitzgerald will be a fixture in the San Franciso Giants lineup this year but appears to be in the bottom third of the order for now. With a hot start and some power in the bat, that could easily change if players like Mike Yastrzemski or Jung Hoo Lee get off to slow starts.
For more of the great fantasy baseball rankings and analysis you’ve come to expect from FantraxHQ, check out our full 2025 Fantasy Baseball Draft Kit! We’re here for you all the way up until Opening Day and then on into your championship run.
