Every new MLB season brings a host of rookies, and a handful of them always emerge as bona fide stars as the year unfolds.

Any rookie on the Opening Day roster faces added scrutiny as fans try to zero in on the next big thing for their favorite club.

With that in mind, we've taken a stroll across the MLB landscape and provided a team-by-team breakdown of the rookies suiting up for their big league squad in the early going.

Included is a look at some notable early performers and analysis of how they might fit into the MLB picture.

Enjoy!

AL East

Baltimore Orioles

Rookies: SP Dean Kremer, LF Ryan Mountcastle, RP Mac Sceroler, RP Tyler Wells, SP Bruce Zimmermann

Among the American League Rookie of the Year front-runners after a strong September showing last year, Ryan Mountcastle is off to a slow start at the plate (4-for-24, 9 K). The 24-year-old will have a long leash as the everyday left fielder and cleanup hitter.

The O's will likely shuffle through a number of starting pitchers, and left-hander Bruce Zimmerman made a strong first impression with four hits and three runs allowed in six innings, while right-hander Dean Kremer lasted just three innings in his first start. Rule 5 picks Mac Sceroler and Tyler Wells have allowed one run in 4.2 innings spanning three appearances.

Boston Red Sox

Rookies: 1B Bobby Dalbec, SP Tanner Houck, RP Hirokazu Sawamura, RP Garrett Whitlock

After a torrid spring, Bobby Dalbec is still searching for his first extra-base hit of the year. If he continues to struggle, Michael Chavis could get a crack at the first base job, but he still has plenty of time to find his footing.

Tanner Houck has struck out 10 batters and walked only one while allowing two earned runs in six innings spanning one start and one relief appearance, though the team optioned him to make room for Eduardo Rodriguez's return. In the bullpen, Japanese import Hirokazu Sawamura and Rule 5 pick Garrett Whitlock have combined for 6.1 scoreless innings in four appearances.

New York Yankees

Rookies: None

We will almost certainly see right-hander Deivi Garcia on the MLB roster at some point, whether it's as a starter or a multi-inning reliever. For now, keeping him at the alternate site will allow him to be stretched out as a starter while keeping his innings total for the year under control.

Tampa Bay Rays

Rookies: RF Randy Arozarena, 1B/3B Kevin Padlo

It's easy to forget that, despite last year's postseason heroics, Randy Arozarena still holds rookie status. Prior to slugging 10 home runs in 20 games during last year's playoffs, he had tallied just 84 MLB regular-season at-bats. After striking out 11 times in 39 plate appearances during spring training, he's off to a 6-for-20 start with one double and seven punchouts in 22 trips to the plate while hitting in the middle of the Tampa Bay lineup.

A knee injury to Ji-Man Choi opened the door for Kevin Padlo to make the roster, and he's 0-for-2 with two walks.

Toronto Blue Jays

Rookies: C Alejandro Kirk, RP Julian Merryweather, RP Joel Payamps, SP T.J. Zeuch

The No. 21 overall pick in the 2016 draft, right-hander T.J. Zeuch has been a forgotten man in a Toronto system that has churned out high-profile talent. After seeing sporadic MLB action the past two seasons, he broke camp with a rotation spot thanks to a handful of injuries and tossed four scoreless innings in his 2021 debut.

Hard-throwing Julian Merryweather has struck out five in two perfect innings while nailing down a pair of save opportunities, and he looks like a rising star in the bullpen. Alejandro Kirk is 0-for-7 to start the year, and Joel Payamps has tossed 1.1 no-hit innings in relief.

AL Central

Chicago White Sox

Rookies: RP Garrett Crochet, RP Michael Kopech, 2B Nick Madrigal, DH Yermin Mercedes, LF Andrew Vaughn

For a team with title aspirations, the White Sox are leaning heavily on a number of rookies to begin the year.

Nick Madrigal (5-for-21) and Andrew Vaughn (2-for-13) could both move up in the batting order as the season progresses, but it's 28-year-old rookie Yermin Mercedes (13-for-23, 3 2B, HR) who is swinging the hottest bat on the team.

In the bullpen, flamethrowers Garrett Crochet (3.1 IP, 1 H, 0 ER, 5 K) and Michael Kopech (4.0 IP, 1 H, 0 ER, 8 K) are dynamic multi-inning weapons who will give opposing hitters fits all year.

Cleveland

Rookies: RP Emmanuel Clase, RP Triston McKenzie, RP Trevor Stephan

Lanky right-hander Triston McKenzie will eventually be the No. 5 starter in the Cleveland rotation, but the team can with a four-man staff to start the year, so he was used for 3.2 innings of relief in his season debut.

Hard-throwing Emmanuel Clase has fanned three in two perfect innings, and he could emerge as a key setup arm ahead of James Karinchak. Rule 5 pick Trevor Stephan made it through his MLB debut unscathed.

Detroit Tigers

Rookies: LF Akil Baddoo, SP Casey Mize, SP Tarik Skubal

Outfielder Akil Baddoo has been one of the best stories of baseball's first week, going 5-for-11 with two home runs and seven RBI after playing his way onto the roster as a Rule 5 pick. With plenty of available playing time in the outfield, he'll be given regular at-bats as long as he's hitting.

Top prospects Casey Mize (4.0 IP, 5 H, 1 ER) and Tarik Skubal (5.1 IP, 4 H, 2 ER) both started their first full seasons in the Detroit rotation on a positive note.

Kansas City Royals

Rookies: RP Jake Brentz, RF Kyle Isbel, RP Carlos Hernandez

Outfielder Kyle Isbel was a third-round pick in the same 2018 draft that saw the Royals select Brady Singer, Jackson Kowar, Kris Bubic and Daniel Lynch in the first round. An oblique injury to Adalberto Mondesi opened the door for him to claim the starting right field job, with Whit Merrifield shifting to second base and Nicky Lopez moving to shortstop. The 24-year-old is 5-for-17 with a triple and eight strikeouts.

Carlos Hernandez and Jake Brentz are part of what could be a revolving-door bullpen this year.

Minnesota Twins

Rookies: C Ryan Jeffers, LF Brent Rooker

Catcher Ryan Jeffers and outfielder Brent Rooker are a combined 3-for-21 with 13 strikeouts to start the year.

Jeffers will continue to platoon with Mitch Garver behind the plate, while Rooker landed on the injured list on Wednesday with a neck strain. Alex Kirilloff should soon get the call to assume everyday duties in left field.

AL West

Houston Astros

Rookies: RP Bryan Abreu, SP Luis Garcia, OF Chas McCormick, IF Robel Garcia

The Astros have turned to Luis Garcia for the No. 5 starter spot with Framber Valdez (finger) on the injured list, and he allowed four hits and two earned runs in 3.1 innings in his first start of the year.

Bryan Abreu (2 G, 1 HLD, 4.1 IP, 2 H, 0 ER) has the electric stuff to be a key setup reliever, while Chas McCormick and Robel Garcia are solid bench pieces who could stick around all year.

Los Angeles Angels

Rookies: RP Chris Rodriguez, IF Jose Rojas

After battling arm issues the past several years, Chris Rodriguez is finally healthy and flashing the potential that has long made him the highest-ceiling arm in the Angels system with six strikeouts and one earned run allowed in 4.2 innings. His innings will be monitored closely, but his talent is undeniable.

Jose Rojas won a bench job with a strong spring, but he's just 0-for-3 with a walk.

Oakland Athletics

Rookies: OF Seth Brown, C Aramis Garcia, RP A.J. Puk, OF Ka'ai Tom

With Sean Murphy still getting up to speed after suffering a collapsed lung during the offseason, Aramis Garcia has been splitting the starting catcher duties in the early going. The longtime prospect is 0-for-11 with four strikeouts.

Rule 5 pick Ka'ai Tom and slugger Seth Brown are serving as bench bats, while oft-injured lefty A.J. Puk is being brought along slowly in a relief role. He allowed one hit and three walks in 3.1 scoreless innings out of the bullpen in his first appearance, and he could pitch his way into the rotation.

Seattle Mariners

Rookies: OF Braden Bishop, LF Jake Fraley, OF Sam Haggerty, CF Taylor Trammell, RP Will Vest

A spring knee injury to Kyle Lewis and a wide-open left field situation has created ample opportunity in the Seattle outfield. Unfortunately, the trio of Taylor Trammell, Jake Fraley and Sam Haggerty have started the year a combined 3-for-35 with 16 strikeouts. Braden Bishop was recalled on Wednesday after Fraley was placed on the injured list with a strained hamstring.

Rule 5 pick Will Vest has already made three relief appearances, allowing four hits and one earned run in 4.1 innings and earning his first MLB win Wednesday.

Texas Rangers

Rookies: SP Kohei Arihara, RP Kyle Cody, RP Brett de Geus, SP Dane Dunning, C Jonah Heim, RP John King, RP Josh Sborz, CF Leody Taveras, OF Eli White

Need further proof the Rangers are in full-blown rebuilding mode? Nine rookies dot the 26-man roster, including four relievers (Kyle Cody, Brett de Geus, John King and Josh Sborz) and two starters (Kohei Arihara and Dane Dunning).

Dunning made seven strong starts for the White Sox down the stretch last year before he was acquired in the Lance Lynn deal, while Arihara is 28 years old with six seasons in the Japanese League under his belt, so those two do have more experience than most rookies.

Leody Taveras (2-for-19, 12 Ks) looks like someone who would benefit from further time in the minors, while Jonah Heim and Eli White should be solid part-time pieces this season.

NL East

Atlanta Braves

Rookies: SP Ian Anderson, C Alex Jackson, CF Cristian Pache

After they were thrust into the key roles during Atlanta's postseason run last year, right-hander Ian Anderson and center fielder Cristian Pache both broke camp with starting roles this spring.

Anderson looked the part of a NL Rookie of the Year candidate when he allowed four hits and one earned run while striking out seven over five innings in his season debut. Pache is off to a 2-for-16 start with eight strikeouts, but his glove will give him a long leash offensively.

Backup catcher Alex Jackson went 0-for-2 in his first start of the year Wednesday.

Miami Marlins

Rookies: RP Paul Campbell, 2B Jazz Chisholm, RP Zach Pop, SP Trevor Rogers

A strong spring won Jazz Chisholm the starting second base job, and he has a double and triple in his first 20 plate appearances. Keep in mind the Marlins gave up Zac Gallen to acquire him from the D-backs.

Left-hander Trevor Rogers was wild in his 2021 debut with four walks and two hits allowed over four innings, but he limited the damage to two earned runs while fanning six. Zach Pop and right-hander Paul Campbell are simply bullpen depth.

New York Mets

Rookies: None

Left-hander Thomas Szapucki and outfielder Khalil Lee could both see the majors before the All-Star break, but the Mets do not have any rookies on the MLB roster.

Philadelphia Phillies

Rookies: RP Connor Brogdon

Connor Brogdon is on pace to win 81 games this season, tallying three wins out of the Philadelphia bullpen through the team's first six games. The 26-year-old won't maintain that pace, but he does have the stuff to be a key relief arm.

He posted a 3.97 ERA with 17 strikeouts in 11.1 innings in his first taste of the big leagues last year.

Washington Nationals

Rookies: C Tres Barrera, RP Sam Clay, OF Cody Wilson

With catchers Alex Avila and Yan Gomes and outfielder Kyle Schwarber all sidelined under COVID-19 protocols, Tres Barrera and Cody Wilson are getting some run on the MLB roster to begin the year.

Sam Clay, 27, worked a scoreless inning and struck out two in his MLB debut Wednesday.

NL Central

Chicago Cubs

Rookies: SP Adbert Alzolay

The Cubs went with Adbert Alzolay over Alec Mills for the No. 5 starter spot, and he surrendered four earned runs over five innings in his first start of the year. The 26-year-old had a 2.95 ERA with 29 strikeouts in 21.1 innings last season, and he'll be given every chance to prove he can be a long-term rotation piece.

Cincinnati Reds

Rookies: SP Jose De Leon, 2B Jonathan India, C Tyler Stephenson

It's a long season, but Jonathan India is making a nice early case to be a contender for NL Rookie of the Year honors. The No. 5 pick in the 2018 draft disappointed in the minors, but he's off to a 10-for-21 start with a pair of extra-base hits as the everyday second baseman. The late-spring infield realignment opened a spot for him, and he doesn't look like he'll be giving it up anytime soon.

Catcher Tyler Stephenson is off to a 5-for-11 start and hit his first home run of the season Wednesday. Don't be surprised if he steadily claims a bigger piece of the platoon with Tucker Barnhart.

Filling in for the injured Sonny Gray (back), former top prospect Jose De Leon allowed three hits and two earned runs while striking out nine over five innings in his first MLB start since 2016.

Milwaukee Brewers

Rookies: RP J.P. Feyereisen

Reliever J.P. Feyereisen had a brilliant spring, allowing just one hit and two walks while piling up 17 strikeouts in 9.2 innings to earn a spot in the Milwaukee bullpen.

The 28-year-old has carried that strong performance into the regular season, allowing one hit and one unearned run while appearing in four of the team's first six games.

Pittsburgh Pirates

Rookies: RP David Bednar, RP Wil Crowe, IF/OF Phillip Evans, RP Luis Oviedo

The Pirates acquired David Bednar in the Joe Musgrove trade and Wil Crowe in the Josh Bell trade, and both pitchers started the season in the MLB bullpen. Bednar has future closer potential, while Crowe has been developed as a starter and could eventually slot into the rotation.

Rule 5 pick Luis Oviedo jumped straight from Single-A to the majors, but he's allowed just one hit with five strikeouts in three innings.

A wrist injury to Ke'Bryan Hayes has opened the door for Phillip Evans to see some additional playing time and the 28-year-old is 7-for-16 with two home runs in the early going. He also worked a perfect inning in relief in a 14-1 blowout loss on Tuesday.

St. Louis Cardinals

Rookies: CF Dylan Carlson, 1B/OF John Nogowski, IF Edmundo Sosa, RF Justin Williams

Top prospect Dylan Carlson is living up to the hype, slugging three home runs in his first 23 plate appearances, including a grand slam Wednesday. Of course, those are also his only three hits of the year.

Justin Williams has been overmatched while filling in for the injured Harrison Bader (forearm), going 1-for-12 with six strikeouts. Spring star John Nogowski and out-of-options Edmundo Sosa have been used sparingly off the bench.

NL West

Arizona Diamondbacks

Rookies: UT Wyatt Mathisen, SS Geraldo Perdomo, RP Matt Peacock, RF Pavin Smith, RP Riley Smith, SP Taylor Widener

One of the best performances from any rookie during the first week of the season came from Taylor Widener, who tossed six scoreless innings in the first start of his MLB career. The 26-year-old made 12 appearances out of the bullpen last year.

Injuries to right fielder Kole Calhoun (knee) and shortstop Nick Ahmed (knee) opened the door for Pavin Smith and Geraldo Perdomo to see some early big league action. They've gone a combined 3-for-22 but are gaining valuable experience. Utility man Wyatt Mathisen fills out the bench.

Relievers Riley Smith (5.0 IP, 5 H, 2 ER) and Matt Peacock (3.0 IP, 1 H, 0 ER) have both been used to chew through innings behind early exits from the team's starter. That could be the role they fill all season.

Colorado Rockies

Rookies: RP Ben Bowden, OF Yonathan Daza, C Dom Nunez, RP Jordan Sheffield

Catcher Dom Nunez has the offensive upside to claim the starting backstop job following the club's decision to non-tender Tony Wolters, and he's homered twice in three games to open the year. Don't be surprised if he pushes Elias Diaz into the backup role. Outfielder Yonathan Daza remains a defensive standout best suited for fourth-outfielder duties.

Rule 5 pick Jordan Sheffield has two scoreless appearances under his belt, while left-hander Ben Bowden has been knocked around in both of his appearances, allowing six hits and four earned runs in 2.1 innings.

Los Angeles Dodgers

Rookies: IF Zach McKinstry

The versatile Zach McKinstry nearly played his way onto the Opening Day roster last spring, and the offseason departure of Enrique Hernandez has cleared a path for him to fill a utility role on the Dodgers bench.

He had started four straight games at three different positions entering play Thursday and was off to a 6-for-20 start with three doubles and one home run. The 25-year-old can be a key piece of the puzzle for the defending champs in 2021.

San Diego Padres

Rookies: C Luis Campusano, RP Nabil Crismatt, IF Ha-Seong Kim, IF Tucupita Marcano, OF Jorge Mateo, 1B/OF Brian O'Grady, RP Ryan Weathers

Never shy about pushing young players, the Padres started the season with Tucupita Marcano (21 years old), Ryan Weathers (21 years old) and Luis Campusano (22 years old) on the Opening Day roster. Those three players will fill supporting roles for now, but all three have impact upside.

Nabil Crismatt earned a spot in the bullpen with a strong spring, and he's tallied three scoreless innings, Brian O'Grady got the call to replace Fernando Tatis Jr. (shoulder) on the active roster when the latter hit the injured list, and speedy Jorge Mateo is 4-for-13 with two doubles to open the year.

The X-factor here is former KBO star Ha-Seong Kim, who has taken over as the starting shortstop with Tatis sidelined. The 25-year-old is 3-for-15 and still searching for his first extra-base hit, but he posted a .921 OPS with 30 home runs in 138 games last year for the Kiwoom Heroes, so the potential for big things is there.

San Francisco Giants

Rookies: None

It's a bit surprising to see the rebuilding Giants begin the year with zero rookies on their MLB roster, but the youth movement will be in full swing soon. Catcher Joey Bart still holds rookie status and should be back in 2021.

All stats courtesy of Baseball Reference and FanGraphs. Stats accurate heading into play Thursday.