Five most surprising breakout players in this MLB season

5. RHP Jared Jones | Pittsburgh Pirates 

The Pirates have struggled mightily since their stellar start to the season, but Jones continues to be a bright spot. The 2020 second-round pick wasn't expected to make the Opening Day roster out of spring training; however, Jones did just that after not allowing a run and collecting 15 strikeouts across six Grapefruit League appearances. 

Over his first seven career starts, Jones has looked the part of a future ace despite being on an innings restriction, displaying high velocity and impeccable command. In 41 innings, Jones has posted a 2.63 ERA with 52 strikeouts and only five walks. 

The 22-year-old ranks fourth among qualified pitchers in strikeouts per nine innings (11.41) and third in walks per nine innings pitched (1.10).

Advanced metrics show Jones is already one of the more dominant pitchers in baseball. According to Baseball Savant, Jones ranks in the 94th percentile in fastball velocity and strikeout rate, the 95th percentile in walk rate and the 97th percentile in whiff rate. 

Once 2023 No. 1 overall pick Paul Skenes is finally called up, Pittsburgh could have MLB's top pitching duo for the foreseeable future. 

4. Outfielder Colton Cowser | Baltimore Orioles 

Another Oriole enjoying a breakout year, Cowser is an integral part of Baltimore's lineup, arguably the deepest in baseball.

The 2021 first-rounder didn't show much promise in a 26-game stint in the majors last season, producing a slash line of .115/.286/.148 with no home runs and four RBI. Because of these poor results and the fact that the Orioles have several quality outfielders, there was no guarantee Cowser would be on the Opening Day roster.

With everything to lose, Cowser had a terrific spring, posting a .304 batting average across 46 at-bats with six homers and 13 RBI and earning a spot on the Opening Day roster. Over his first 32 games this season, Cowser has shown no signs of slowing, slashing .276/.354/.575 with six home runs and 19 RBI and drawing 10 walks.

For his efforts, Cowser was named the American League Rookie of the Month for April/March. Per MLB.com, Cowser led all rookies in RBI, slugging percentage, OPS, total bases and extra-base hits during the first month of the season. 

3. RHP Kutter Crawford | Boston Red Sox

Crawford, who debuted in 2021, began his career primarily serving as reliever and wasn't particularly effective.

Following a short early-season demotion last season, Crawford began to come into his own as a starter. He finished 2023 with a 4.04 ERA and 1.11 WHIP, the lowest marks of his career to that point, and struck out a career-high 135 batters.

Thanks in part to the addition of new pitching coach Andrew Bailey, Crawford has built on last season's success in a way nobody could have predicted. Through his first seven starts, Crawford has a 1.56 ERA, the second lowest among qualified starters, with 40 strikeouts. Additionally, Crawford's 2.0 bWAR is tied for the major league lead with Philadelphia's Ranger Suarez. 

It'll be challenging for the middling Red Sox (19-16) to make the postseason. However, if their offense starts clicking, the pitching staff is positioned to keep them in contention for much of the season, especially if Crawford continues to perform like a Cy Young candidate. 

2. RHP Reed Garrett | New York Mets

A late bloomer, to say the least, the 31-year-old has overcome quite a few obstacles to emerge as one of the best relievers this season. Garrett, who entered this season with a 7.11 ERA, made his major league debut in 2019, posting an 8.22 ERA over 15.1 innings for the Tigers before being designated for assignment.

After spending two years in Japan, Garrett made nine appearances across parts of two seasons with Washington and Baltimore before New York claimed him last June. The former 16th-round draft pick posted a 5.82 ERA in nine games with the Mets last season, but the team kept him around for 2024, a decision they're surely happy with now.

Although he didn't crack the Opening Day roster, Garrett was called up April 1 and since then has been dominant, posting a 0.50 ERA through his first 12 appearances. Garrett doesn't have the most overwhelming pitch repertoire, though that hasn't been an issue, as his 30 strikeouts rank first among relievers this season. 

1. RHP Mason Miller | Oakland Athletics 

While Garrett's story is compelling in its own right, Miller's journey has been far more improbable. Miller began his collegiate career for Waynesburg (Pa.) University, a Division III program, but he wasn't some under-recruited high schooler who broke out once he got to college. The 24-year-old posted a 7.03 ERA and 7.16 ERA in 2017 and 2018, respectively, and struggled to keep weight on his body and velocity on his fastball.

Following his sophomore season, Miller earned a finance internship at a hospital, which required him to take a drug test. The results ultimately changed the trajectory of his career. Miller's sample was flagged as diluted and it was later revealed that he had Type 1 diabetes, the cause of his weight issues. 

With proper dieting and training, Miller finally broke out and after emerging as one of the best D-III pitchers in 2019 and 2020, he transferred to Gardner-Webb, where he posted a 3.30 ERA.

The A's selected Miller in the third round of the 2021 MLB Draft, and he debuted last season, making 10 appearances (six starts) before moving to the bullpen due to recovery from a UCL sprain. Now, Miller has established himself as MLB's most dominant closer, posting a 1.26 ERA and eight saves while ranking in the 100th percentile in fastball velocity, whiff rate and strikeout rate, per Baseball Savant. 

It's unclear whether frugal Oakland (17-18) will consider trading him, but Miller will surely be highly sought at the trade deadline. 

Honorable mentions: Chicago Cubs first baseman Michael Busch, Milwaukee Brewers second baseman Brice Turang, San Francisco Giants RHP Jordan Hicks, Baltimore Orioles infielder Jordan Westburg