Every MLB season features at least a few under-the-radar players who emerge as surprise contributors.

Whether it's young players on the rise, journeymen receiving an extended look or veterans proving they still have something left, there are a few hidden gems on every roster.

The idea here is to highlight one player from each team who has received little to no national recognition for their contributions this season.

American League East

Baltimore Orioles: LHP Cionel Pérez

A highly touted prospect out of Cuba, Pérez never developed as hoped with the Houston Astros and struggled to a 6.38 ERA in 25 appearances with the Cincinnati Reds in 2021. The Orioles claimed him off waivers in November, and he has emerged as one of their top bullpen arms, posting a 1.53 ERA and 1.19 WHIP with 21 holds in 55 appearances.

Boston Red Sox: RF Rob Refsnyder

Playing with his eighth team since the New York Yankees traded him before the 2017 deadline, Refsnyder is enjoying his best season. The 31-year-old is hitting .314/.393/.488 for a 145 OPS+ with 13 extra-base hits in 140 plate appearances and has played all three outfield spots.

New York Yankees: RHP Ron Marinaccio

Marinaccio emerged as a prospect on the rise in 2021 when he posted a 2.04 ERA with 105 strikeouts in 66.1 innings in the upper levels of the minors and is quietly having an excellent rookie season. The 27-year-old has a 1.80 ERA and 0.94 WHIP with 10.5 strikeouts per nine innings in 31 appearances.

Tampa Bay Rays: 3B Yandy Díaz

Does anyone outside of Tampa realize how good Yandy Díaz has been this season? His 3.3 WAR ranks eighth among third basemen, and his .396 on-base percentage is fifth overall. He has emerged as a terrific table-setter atop the lineup.

Toronto Blue Jays: RHP Ross Stripling

The Blue Jays have had to navigate injuries (Hyun Jin Ryu) and ineffectiveness (Yusei Kikuchi) with their starting rotation, so Stripling's ability to fill a swingman role has been invaluable. The 32-year-old has a 3.03 ERA and 1.04 WHIP with 94 strikeouts in 107 innings spanning 19 starts and eight relief appearances.

American League Central

Chicago White Sox: C Seby Zavala

Zavala has outperformed high-priced starting catcher Yasmani Grandal by a wide margin, hitting .281/.353/.392 for a 112 OPS+ with 13 extra-base hits and 1.0 WAR in 50 games. The 29-year-old also ranks as one of the best pitch-framers in baseball and is still two years from reaching arbitration eligibility.

Cleveland Guardians: RHP Trevor Stephan

Plucked from the Yankees system in the 2020 Rule 5 draft, Stephan finished his rookie season with a 4.41 ERA in 43 appearances. The 26-year-old has carved out a high-leverage role this year, improving his strikeout rate (10.7 to 11.7 K/9) and walk rate (4.4 to 2.2 BB/9) en route to a 2.58 ERA and 1.18 WHIP with 12 holds in 52 appearances.

Detroit Tigers: RHP Drew Hutchison

A promising young starter in the Toronto organization once upon a time, Hutchison spent the 2019 season in the minors and 2020 in independent ball before returning to the majors last year with a 2.11 ERA in 21.1 innings. The 32-year-old has pitched his way into the rotation and ranks second on the team with 82 innings, logging a 4.06 ERA in 13 starts and 10 relief appearances.

Kansas City Royals: C/OF MJ Melendez

Lost in the shuffle of Bobby Witt Jr.'s solid rookie season, Melendez is having a strong debut of his own. The 23-year-old has a 105 OPS+ with 16 doubles, 15 home runs and 51 RBI in 421 plate appearances, and his terrific 12.6 percent walk rate has led to a surprising role as leadoff hitter. He has also held his own while learning to play right and left field.

Minnesota Twins: LF Kyle Garlick

A 28th-round pick in the 2015 draft, Garlick entered the season having played 78 games for the Twins, Los Angeles Dodgers and Philadelphia Phillies. Injuries to Byron Buxton, Trevor Larnach and Alex Kirilloff opened the door, and the 30-year-old has responded with a 138 OPS+ and nine home runs in 133 plate appearances.

American League West

Houston Astros: RHP Bryan Abreu

Armed with a fastball that averages 97.3 mph and a wipeout slider, Abreu has always had late-game stuff, but he struggled to a 5.75 ERA in 31 appearances last season. The 25-year-old has been dominant this season, posting a 1.95 ERA and 1.13 WHIP with a 35.3 percent strikeout rate that ranks seventh among pitchers who have thrown at least 50 innings.

Los Angeles Angels: 2B/3B Luis Rengifo

A .216/.293/.325 career hitter in 702 plate appearances heading into the season, Rengifo is batting .273/.304/.433 for a 107 OPS+ with 19 doubles, 11 home runs and 40 RBI in 392 trips to the plate. The 25-year-old has also provided valuable defensive versatility with starts at second base (62), third base (19) and shortstop (13).

Oakland Athletics: LHP A.J. Puk

Once one of baseball's elite pitching prospects, Puk has struggled with injuries over the years, and the Athletics abandoned developing him as a starter. The 27-year-old has pitched his way into the closer's role, posting a 2.43 ERA and 1.06 WHIP with 10.5 strikeouts per nine innings, four saves and 17 holds in 52 appearances.

Seattle Mariners: RHP Andrés Muñoz

With a fastball that averages 100.1 mph and a slider that has generated 67 strikeouts and a 50.9 percent whiff rate, Muñoz has some of the best stuff in baseball. The 23-year-old has a 2.78 ERA and 0.95 WHIP with 13.9 strikeouts per nine innings and 19 holds in 54 appearances. His 39.9 percent strikeout rate trails only Edwin Díaz's 49.0 percent and Ryan Helsley's 40.6 percent among pitchers who have thrown at least 50 innings.

Texas Rangers: LHP Matt Moore

Moore was the No. 1 prospect in baseball at the start of 2012, according to MLB.com—ahead of Bryce Harper and Mike Trout. He looked like an ace in the making when he reached the majors, but injuries derailed his development, and he struggled to a 6.29 ERA in 73 innings with the Phillies last year. The 33-year-old, however, has made good on a minor league deal with the Rangers, posting a 2.24 ERA and 9.8 strikeouts per nine innings in 49 appearances.

National League East

Atlanta Braves: RHP Jesse Chavez

Chavez signed a one-year deal with the Chicago Cubs in March. He pitched three games with the club before he was traded to the Braves, and then he was traded again to the Los Angeles Angels at the deadline in the deal that brought Raisel Iglesias to Atlanta—only to return when he was claimed off waivers Aug. 30. In his two stints, he has a 1.96 ERA in 33 appearances.

Miami Marlins: 3B/2B Jon Berti

The speedy Berti leads the majors with 32 steals and has been a 2.3-WAR player while playing third base, second base, left field, shortstop and center field. The 32-year-old has always had elite wheels, but he now also has a 104 OPS+ in 292 plate appearances with solid defensive metrics everywhere he has lined up.

New York Mets: RHP Trevor Williams

A throw-in piece of the blockbuster deal that sent Javier Báez to the Mets for prospect Pete Crow-Armstrong at the 2021 deadline, Williams has been a valuable swingman. The 30-year-old has a 2.92 ERA in 74 innings spanning nine starts and 15 relief appearances and has logged a 0.98 ERA in 18.1 frames since the All-Star break.

Philadelphia Phillies: DH Darick Hall

The Phillies turned to Hall to fill their designated hitter void when Bryce Harper landed on the injured list, and he posted a 133 OPS+ with eight doubles and nine home runs in 135 plate appearances. The 27-year-old also has an .827 OPS with 21 home runs and 72 RBI in 83 games at Triple-A.

Washington Nationals: 1B/RF Joey Meneses

After 894 games and 3,557 plate appearances in the minors, Meneses finally got his chance in the big leagues after Juan Soto was traded. The 30-year-old made his debut Aug. 2 and is hitting .339/.371/.568 with six doubles, seven home runs and 16 RBI in 124 plate appearances.

National League Central

Chicago Cubs: LHP Brandon Hughes

Drafted as an outfielder in 2017, Hughes moved to the mound in 2019 and pitched his way up the minor league ladder. The 26-year-old threw 16.2 scoreless innings with a 22-to-3 strikeout-to-walk ratio in Double-A and Triple-A before making his debut May 17 and has a 3.30 ERA and 1.01 WHIP with 11.5 strikeouts per nine innings and three saves in 44 appearances.

Cincinnati Reds: CF TJ Friedl

Signed as an undrafted free agent in 2016, Friedl is getting his first extended chance and has been on fire during the second half. The 27-year-old is hitting .404/.458/.808 with two doubles, two triples and five home runs in 59 plate appearances since the All-Star break and will get a long look over the final month of the season.

Milwaukee Brewers: LHP Hoby Milner

Milner joined the Brewers as a free agent after the 2020 season and logged a 5.40 ERA in 19 appearances last season. The 31-year-old has been their go-to second bullpen lefty this season, employing a new sinker-heavy approach to post a 3.83 ERA and 1.15 WHIP with eight holds in 56 appearances.

Pittsburgh Pirates: RHP Chase De Jong

With a 1.86 ERA and 0.98 WHIP in 58.0 innings, De Jong is tops among pitchers on the Pirates' active roster with 1.8 WAR. The 28-year-old has recorded more than three outs in 25 of his 32 appearances, tallying four wins and two holds as a bright spot for the staff.

St. Louis Cardinals: IF/OF Brendan Donovan

The No. 13 prospect in the Cardinals system when the season began, Donovan has been one of the best super-utility players in baseball. The 25-year-old is hitting .287 with a .391 on-base percentage and 20 extra-base hits in 364 plate appearances and has started at third base (16), second base (16), left field (15), right field (15), designated hitter (10), first base (6) and shortstop (6). His 2.6 WAR ranks fourth on the roster.

National League West

Arizona Diamondbacks: LHP Joe Mantiply

Despite the fact that he is a first-time All-Star, Mantiply has still flown under the radar with a fantastic breakout season for the D-backs. The 31-year-old journeyman has a 2.85 ERA, 1.01 WHIP and 55-to-4 strikeout-to-walk ratio in 53.2 innings and is one of eight pitchers with at least 60 appearances.

Colorado Rockies: SS José Iglesias

The Rockies gave Iglesias a one-year, $5 million deal to fill the shortstop void left by the departure of Trevor Story, and he is hitting .300/.337/.392 with 30 doubles and 1.3 WAR in 114 games. The 32-year-old ranks seventh in the National League batting title race and has been one of the few bright spots in another lost year for Colorado.

Los Angeles Dodgers: OF Trayce Thompson

The Dodgers acquired Thompson from the Tigers for cash considerations in June after Mookie Betts landed on the injured list, and he has gone from a depth addition to an asset. The 31-year-old is hitting .285/.380/.549 for a 153 OPS+ with 12 doubles, eight home runs and 29 RBI in 166 plate appearances.

San Diego Padres: SS Ha-Seong Kim

With Fernando Tatis Jr. sidelined, Kim has filled the everyday shortstop role, responding with a 4.0-WAR season that ranks sixth among shortstops. The 26-year-old has a 106 OPS+ with 34 extra-base hits, but he's been even more valuable in the field with six defensive runs saved and a 6.3 UZR/150.

San Francisco Giants: RHP John Brebbia

The Giants gave Brebbia a one-year, $800,000 deal after the 2020 season while he rehabbed from Tommy John surgery, and he logged a 5.89 ERA in 18 appearances after returning. That investment is proving fruitful, as he has a 3.04 ERA with 16 holds in an MLB-leading 63 appearances. He is still controllable via arbitration for one more year.

Stats courtesy of Baseball Reference and accurate through Monday.