15 MLB Prospects Poised for Breakout Rookie Seasons in 2026 – Sleepers You Need to Know

By Oliver Wiener January 09, 2026 06:15

As spring training camps open in the coming weeks, the 2026 MLB season promises another wave of exciting rookies ready to make noise. While the spotlight often shines on top prospects like Konnor Griffin (Pirates) or Kevin McGonigle (Tigers) both consensus top-5 talents with realistic paths to Opening Day the real fun lies in the sleepers. These are the under-the-radar names who could explode onto the scene, delivering fantasy gold, Rookie of the Year contention, or unexpected impact for rebuilding clubs.

Drawing from recent MLB Pipeline updates, Baseball America sleeper lists, and front-office buzz as of early January 2026, here are 15 prospects positioned for potential breakout rookie campaigns. Many are close to MLB-ready, with strong 2025 performances in the upper minors or AFL, and organizational needs paving the way.

Parker Messick, LHP, Cleveland Guardians Messick, a 2022 second-rounder from Florida State, flashed elite polish late in 2025 with a 2.72 ERA and 38/6 K/BB in 39 2/3 innings across seven late-season MLB starts. His mid-80s changeup is one of the best in the minors, complementing a low-90s fastball and sharp slider. With Cleveland's rotation depth, he could lock in a spot early. "His cambio makes everything play up," one scout told MLB.com.
Joshua Baez, OF, St. Louis Cardinals The 2021 second-rounder overcame early injuries and swing-and-miss concerns to post a .287/.384/.500 line with 20 HR and 54 SB across High-A and Double-A in 2025. His raw power and plus arm in right field make him a five-tool sleeper. Baez could force his way into the outfield mix if injuries hit.
Josh Adamczewski, OF, Milwaukee Brewers A 15th-round steal from 2023, Adamczewski exemplifies Milwaukee's draft-and-develop magic. His late-round signing ($252,500) belies plus tools, and he's a candidate for a massive leap onto the Top 100. Watch for him to climb quickly in a system known for unearthing gems.
Luis De León, LHP, Baltimore Orioles Signed for just $30,000 out of the Dominican Republic in 2021, De León has blossomed into a high-upside arm. His breakout potential stems from improved command and stuff, making him a sneaky candidate for a mid-2026 call-up in Baltimore's pitching-rich system.
Sal Stewart, 3B, Cincinnati Reds A frequent mention in ROY discussions, Stewart's bat-to-ball skills and power could shine in the hitter-friendly Great American Ball Park. MLB Pipeline execs see him as a factor in the NL Central rookie race.
JJ Wetherholt, SS/2B/3B, St. Louis Cardinals The versatile infielder dominated in 2025, positioning him for a potential Opening Day role. His contact ability and positional flexibility make him a strong ROY contender, per Pipeline predictions.
Samuel Basallo, C/DH, Baltimore Orioles Basallo's power and hit tool have scouts buzzing about a 2026 debut. As Baltimore's top catching prospect, he could provide immediate offensive pop behind the plate or at DH.
Colt Emerson, SS, Seattle Mariners The young shortstop's advanced approach and tools suggest a fast track. With Seattle needing infield help, Emerson could debut and contribute significantly.
Carter Jensen, C, Kansas City Royals Jensen's defensive prowess and improving bat make him a sleeper for Royals' catching depth. A strong spring could earn him early playing time.
Bubba Chandler, RHP, Pittsburgh Pirates Chandler's electric stuff positions him as a potential midseason impact arm. In a rotation needing youth, he could emerge as a high-upside rookie.
Zyhir Hope, OF, Los Angeles Dodgers Hope reached Double-A in 2025 with intriguing hitting tools. In LA's star-studded system, a breakout could come via injuries or trades opening spots.
Josue De Paula, OF, Los Angeles Dodgers Another Dodgers outfield prospect with a strong profile who advanced quickly. His power-speed combo makes him a fantasy sleeper.
Trey Yesavage, RHP, Toronto Blue Jays Yesavage dominated late in 2025 and postseason play, earning ROY favorite status. His polish could lead to an early rotation role.
Nolan McLean, RHP, New York Mets McLean's late-2025 surge makes him another ROY frontrunner. The Mets' need for arms could accelerate his debut.
Enddy Azocar, OF, Boston Red Sox A teenage breakout with massive exit velocity gains in 2025, Azocar is a high-upside sleeper outside Boston's Top 10. His power development could yield quick results.

These prospects represent the hidden gems in a loaded 2026 rookie class. Many sit just outside organizational Top 10s or lack the hype of Griffin and McGonigle, but their tools, proximity, and team contexts scream breakout. As one MLB exec told Pipeline, "The sleepers often become the stories." Keep an eye on spring training these 15 could be the next wave of rookies turning heads.