Most Improved 2026: The Bowman Autos Making the Biggest Year-Over-Year Jumps

An analytics look at who has climbed the most from 2025 to 2026, and how I built the list.

Stat-line improvement is one of the cleanest signals in the prospect world, and it is one of the hardest to eyeball across a few hundred names. So I built a way to measure it directly.

I took every hitter and pitcher who has a Bowman autograph and logged at least 100 plate appearances (or batters faced, for the arms) in both 2025 and 2026. I kept only active prospects, the guys still working through the minors rather than the ones who have already graduated. That left a little over 300 hitters and just under 100 arms.

For the hitters I compared five things season over season: power (ISO), overall production (OPS), walk rate, strikeout rate, and swinging-strike rate, which is the share of pitches a batter swings through. For the arms I flipped it to the pitcher's side: strikeout rate, walk rate, the swings-and-misses they generate, ERA, and home runs allowed. Power carries the most weight on the hitting side. Then I layered in two adjustments. If a player improved while jumping to a higher level, that counts for more. Repeat the same level both years and you give a little back. Young for your level helps, old for your level hurts.

Then I sorted by how far each name moved. Here are the five hitters and five arms at the very top.

The Hitters

Jaison Chourio

A 21-year-old who went from contact-first to a real power line at Double-A.

Chourio's 2025 was a patient, punchless line. The walk rate was already excellent, but a .049 ISO meant almost nothing was leaving the yard. In 2026 the power showed up all at once, with the ISO climbing to .198 and the OPS jumping 280 points, and he did it while cutting his strikeout rate to 16 percent and moving up to Double-A. Doing more damage on contact while whiffing less, at a higher level, at age 21, is the exact shape this list is built to find.

His 2026 production grades at a 144 on our level-and-age-adjusted scale at Double-A, where 100 is average. The Bowman 1st auto sits around $31 raw and $89 in a PSA 10.

Chase Harlan

An OPS over 1.000 at 19 years old.

Harlan already hit for power in 2025. In 2026 he added everything around it. The walk rate climbed to 15 percent, the strikeouts came down, and the ISO pushed up to .248 for a line that runs past a 1.000 OPS. His swinging-strike rate sits at a strong 10.4 percent, down from 13.4, so the contact gains look real rather than lucky, and the trend across every category points the same direction. He grades at a 152 in full-season work, the best mark of the hitters here. The auto runs about $45 raw and $148 in a PSA 10.

Juan Flores

The cheapest entry on the list, and a repeat-level riser.

Flores is the example I point to when explaining why repeating a level matters in the math. He ran it back at High-A both years, so he gets no bonus for a level jump, and he still finished near the top on raw improvement. The ISO nearly doubled, the strikeout rate fell six points, and the walk rate ticked up. The catch is that he is doing it as a repeater rather than a climber, which the system docks slightly. His 2026 line grades at a 111. The auto is the quietest market of this group at roughly $7 raw and $25 graded.

Felnin Celesten

A switch-hitting shortstop who started turning his tools into a stat line.

Celesten came in as a big-bonus name whose production had lagged the hype. In 2026 the gap started to close, with gains in all five categories and a move up to High-A. The walk rate jumped almost four points and the strikeouts dropped, which is the discipline profile you want under a developing power bat. He grades at a 122 in full-season work at 20 years old. Of this group, his auto carries the strongest market, around $76 raw and $160 in a PSA 10.

Cole Carrigg

The biggest contact gain on the board.

Carrigg cut his strikeout rate almost 11 points, the largest contact improvement of any hitter here, and his swinging-strike rate fell to 10.9 percent alongside it. The power came up too, and he climbed from Double-A to Triple-A with a brief look at the top level. At 24 he is on the older side for the group, which the age adjustment accounts for, but the year-over-year jump is real and broad. His Triple-A line grades at a 133. The auto runs about $30 raw and $101 graded.

The Arms

The pitching list reads the same way in reverse: more whiffs, fewer walks, fewer runs. A note before the names. The strongest profiles here are about skills moving in the right direction, and the samples in 2026 are smaller than the hitters', so a few of these are early reads rather than settled cases.

Karson Milbrandt

A strikeout rate north of 35 percent with the ERA to match.

Milbrandt already missed bats in 2025, and in 2026 he pushed the strikeout rate to 35 percent while pushing his swinging-strike rate to nearly 19 percent of all pitches, all the way up at Double-A. The walk rate trimmed and the ERA dropped to 1.24. His full-season Double-A work grades at a 159. The auto is one of the cheaper raw markets at about $4 raw, with graded copies thin enough that I would not read much into the lone PSA 10 comp.

Joe Whitman

The highest grade of any arm on the list.

Whitman is the cleanest profile here: more strikeouts, a sub-7-percent walk rate, more swing-and-miss, and an ERA cut by more than two runs across 60-plus Double-A innings. His 2026 line grades at a 191, the top mark among these arms. The auto sits around $12 raw and $16 in a PSA 10, so the graded premium is slim.

Drue Hackenberg

The biggest ERA swing, on the smallest sample.

Hackenberg's line moved more than anyone's: the ERA fell over four runs, the strikeout rate climbed seven-plus points, and the walks came down five. The honest caveat is the sample, about 25 innings back at Double-A after a rough 2025, so the production grade is still forming. The skills trend is the story here, not the run prevention yet. The auto runs roughly $8 raw and $80 graded.

Jackson Humphries

Skills improving faster than the results.

Humphries is the interesting one. The strikeout rate jumped over 10 points and the swinging-strike rate is up to almost 17 percent of pitches, which is why the model likes him, but the ERA barely moved and the walk rate is still north of 17 percent. That combination, big swing-and-miss gains held back by command, is exactly the kind of profile a stat-line model surfaces before the bottom-line numbers follow. He grades at a 100 at High-A. The auto is around $4 raw and $21 graded.

Levi Sterling

The youngest arm on the list, cutting walks and climbing.

Sterling, 19, made his gains across more innings than he threw in 2025, which is its own kind of progress. The walk rate dropped five points, the strikeouts came up, and the ERA fell two runs while moving up to full-season ball. He grades at a 94, just under average, but the age-for-level adjustment and the level jump carry weight here. The auto runs about $39 raw and $90 in a PSA 10.

What this is, and what it isn't

This is a measurement of change, not a ranking of talent or a set of positions. A name at the top of this list is the one whose 2026 numbers moved the most from 2025, weighted toward power and adjusted for level and age. It does not tell you who the best prospect is, and it does not tell you what any of these cards are worth holding. It tells you whose stat line broke in the right direction, which is a useful place to start a deeper look.

I will revisit this as the sample grows, especially on the arms, where a month of innings can move a profile quickly.

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This is not financial advice. These are cards. The data and analysis are here to inform. You make your own calls.

This article was generated with the assistance of AI and reviewed before publishing. Always verify latest market data, stats, or news.

Published: June 2026