Part of what can elevate a good team to greatness is the performance of players who exceed preseason expectations. This analysis explores some of the best-kept secrets across Major League Baseball (MLB) in 2025. These players might include rising young talents or veterans who are consistently outperforming their historical statistics, providing hope to supporters of struggling teams. This overview is presented from a national perspective, which may mean that certain names may not come as a surprise to avid followers of individual teams. However, for fans seeking to identify the most underappreciated players in the league, this analysis serves as a comprehensive guide.

Starting with the New York Yankees, Fernando Cruz has made an impressive impact, showcasing his potential even amidst injury challenges. Despite dealing with right shoulder inflammation, he recorded a 2.66 ERA over 21 games before his setback. Acquired in the offseason trade that involved Jose Trevino, Cruz demonstrated remarkable strikeout ability with a 13.3 K/9 across 23.2 innings pitched. Meanwhile, the Tampa Bay Rays' José Caballero continued to build on his previous season's performance, where he led the American League with 44 stolen bases. Improving upon his weaknesses, he has successfully stolen 19 bases in 23 attempts this season while elevating his OPS from .630 to .735.

For the Toronto Blue Jays, Addison Barger has emerged as a key player, displaying promise as a long-term asset. After being selected in the sixth round of the 2018 draft, Barger has excelled early in the season with 11 doubles, an .801 OPS, and a 1.2 WAR in 37 games, along with valuable defensive versatility. The Boston Red Sox's Brennan Bernardino has rebounded impressively from a disappointing 2024 season, posting a 1.27 ERA in 27 appearances this season while maintaining a consistent presence in the bullpen. In Baltimore, Bryan Baker exemplified resilience for the Orioles, achieving a 2.88 ERA despite a difficult start to the season, even as his FIP suggests possible regression.

Similarly, Will Vest has provided stability for the Detroit Tigers as a dominant reliever, showing marked improvement this year with a 2.00 ERA and eight saves in 25 appearances. The Cleveland Guardians' Daniel Schneemann has effectively filled a gap following the departure of Andrés Giménez, contributing with seven home runs and a .779 OPS in 46 games, while also providing positional flexibility. In the Minnesota Twins' rotation, Louis Varland has transitioned into a reliable contributor, posting a commendable 2.73 ERA in 29 appearances, a significant improvement from his previous career performance.

The Kansas City Royals have also seen promising development from Noah Cameron, who has established himself as a starter with a remarkable 1.05 ERA in his first four starts. The Chicago White Sox's Mike Vasil, despite some concerns regarding his FIP, has recorded a solid 2.10 ERA, suggesting potential worth monitoring. Gabe Speier of the Seattle Mariners has drastically improved his performance, transforming from a league-average reliever into a standout with a 2.01 ERA in 25 games due to his improved command. In Houston, Bennett Sousa has showcased exceptional potential, containing a 2.50 ERA so far.

The Texas Rangers' acquisition of Robert Garcia appears astute, as he has managed a 2.25 ERA in 28 games this season, proving invaluable after the team faced bullpen challenges. Meanwhile, José Soriano for the Los Angeles Angels has emerged as a reliable starter, boasting a 3.42 ERA across substantial innings pitched since transitioning from a bullpen role. The Athletics' Jacob Wilson is notable for his impressive batting average of .345, positioning him as a potential candidate for the AL Rookie of the Year award despite defensive shortcomings.

In Philadelphia, Tanner Banks has become a key part of a veteran-heavy roster, delivering a respectable 3.28 FIP in 25 appearances, particularly in the absence of suspended reliever José Alvarado. The New York Mets' Reed Garrett has experienced a remarkable turnaround, generating a stellar 0.73 ERA after previously struggling to find consistent success in the majors. Meanwhile, Cole Henry of the Washington Nationals has become a crucial asset, compiling an excellent 2.14 ERA across 18 games for a struggling bullpen. In Atlanta, Daysbel Hernández has shown flashes of brilliance with a 2.25 ERA, although his high walk rate needs addressing.

For the Miami Marlins, Valente Bellozo's early performance has been encouraging, with a solid 2.89 ERA over 28 innings, contributing to a team with limited options. Caleb Thielbar, at 38 years old, has revitalized his career with the Chicago Cubs, achieving a 2.29 ERA this season. Kyle Leahy’s contributions as a setup man for the St. Louis Cardinals have proven pivotal, helping his team surpass initial expectations with a 2.08 ERA. Abner Uribe has continued the legacy of impactful relief pitching in Milwaukee with an impressive 1.65 ERA and 12.2 K/9, exemplifying the Brewers' adept ability to develop talent.

Lyon Richardson has garnered attention with solid performances for the Cincinnati Reds, while Dennis Santana has transformed into a formidable reliever for the Pittsburgh Pirates, boasting a 1.48 ERA that solidifies his status as a potential All-Star and valuable trading asset. The Los Angeles Dodgers' Jack Dreyer has temporarily stabilized their bullpen in the absence of key players with a 2.97 ERA, while Gavin Sheets, now with the San Diego Padres, has rebounded from previous struggles to find success, hitting .269 with an .822 OPS. Lastly, Randy Rodríguez has made a strong case as one of the top relievers in baseball for the San Francisco Giants, while Shelby Miller has thrived during his 13th season with the Arizona Diamondbacks, registering a 1.99 ERA and bolstering their bullpen.

In an overall moment of reflective optimism, even amidst struggles, teams such as the Colorado Rockies can find encouragement in the performance of Jordan Beck, who, in his second MLB season, has managed to record eight home runs and an .810 OPS.