The Orioles on Friday selected the contracts of five of their Top 30 prospects per MLB Pipeline amid a slew of transactions: No. 8 outfielder Yusniel Diaz, No. 9 righty Michael Baumann, No. 11 left-hander Zac Lowther, No. 19 lefty Alexander Wells, No. 25 infielder Rylan Bannon and unranked reliever Isaac Mattson. Their 40-man roster is now full.

Additionally, the O’s cut ties with one of their top sluggers to clear space for their prospects, designating Renato Núñez for assignment. Núñez led the Orioles with 43 homers since the beginning of 2019, mostly in a DH role.

Núñez was a former waiver claim who emerged as a middle-of-the-order regular during the first three seasons of their rebuild. Núñez, 26, was arbitration eligible this winter after hitting .256 with 12 home runs, 31 RBIs and .816 OPS in 52 games in 2020. He paced Baltimore in homers, ranked second on the team in runs and RBIs and third in slugging last summer.

Across 263 games with the Orioles since 2018, Núñez hit .253 with 52 homers and a .764 OPS (108 OPS+). But opportunities for Núñez figured to be limited going forward given the emergence of Anthony Santander in right field, No. 5 prospect Ryan Mountcastle in left and Trey Mancini returning from treatment for Stage 3 colon cancer. Chris Davis remains on the roster as well, and now Diaz is added to an already crowded mix of corner outfielders who will warrant at bats.

Núñez’s lack of a true defensive home also factored into the Orioles’ decision, though he does have limited experience at both first base and third.

"It was a very difficult decision because he’s been such a productive member of our lineup, and he’s been an important member of the club here for the past couple years,” Orioles GM/EVP Mike Elias said. “Ours is not the ideal roster for him in terms of a fit.”

The deadline to shield prospects from Rule 5 selection was 6 p.m. ET on Friday. The Rule 5 Draft is scheduled for Dec. 10.

Players first signed at age 18 or younger must be added to a team's 40-man roster within five seasons or they become eligible through the Rule 5 process; players signed at age 19 or older must be protected within four seasons. Clubs pay $100,000 to select a player in the Major League phase of the Rule 5 Draft. If that player doesn't stay on the 26-man MLB roster for the full season, he must be offered back to his former team for $50,000.

This year, that means an international or high school Draft pick signed in 2016 -- assuming he was 18 or younger as of June 5 of that year -- has to be protected, A college player taken in the '17 Draft is in the same position. The Orioles’ most interesting omissions on Friday were rehabbing reliever Zac Pop and infielder Mason McCoy.

Let’s take a look at the six prospects the O’s protected on Friday, who could all be projected to see Major League action in 2021, and what those decisions mean for their outlook next season and beyond:

OF Yusniel Diaz
MLB Pipeline club ranking: No. 8
2021 Opening Day age: 24

Once the prize of the Manny Machado trade, Diaz is now part of a stable of young outfield prospects the Orioles are excited about, several of whom debuted or got significant run at the big league level in 2020. Diaz likely would’ve reached the Majors last summer had the season been normal length; as it was, he was part of their camp at Double-A Bowie, where he spent most of 2018-19.

Now 24, Diaz still projects as an everyday player at the big league level, seen as a future corner outfielder and potential middle-of-the-order bat. But his path to regular playing time seems complicated in the short-term; he’ll have to perform enough to stand out in a crowded field of outfielders that includes Mountcastle, Santander, Cedric Mullins, Austin Hays, DJ Stewart and Ryan McKenna. The key might be health, as Diaz saw his development stalled due to various muscle injuries since arriving from the Dodgers’ organization.

RHP Michael Baumann
MLB Pipeline club ranking: No. 9
2021 Opening Day age: 25

Baumann was shut down early this summer due to an elbow strain -- but the injury didn’t require surgery and shouldn’t affect his status for 2021. The big righty took as large a leap forward as any O’s prospect two years ago, dominating after a midseason promotion to Double-A Bowie. There is power stuff in Baumann’s 6-foot-4, 225-pound frame, namely his mid-to-upper 90s fastball and wipeout slider. He probably opens 2021 in the Triple-A rotation and is a candidate to reach the Majors by mid-summer, possibly as an impact reliever.

LHP Zac Lowther
MLB Pipeline club ranking: No. 11
2021 Opening Day age: 24

The O’s have had to scour the lower rungs of the free-agent market and waiver wire for rotation depth in recent years. Now they’re nearly ready to mine it from within. Enter Lowther, the strike-throwing southpaw with the invisi-ball whose main skill is getting outs. The O’s second-round pick in 2017 performed at every level prior to the pandemic, spending the entire 2019 season at Double-A Bowie. His best pitch is an ultra-high-spin fastball, which registers in the low-90s but plays up due to Lowther’s pitchability and deceptive delivery. He looks like a lock to start 2021 at Triple-A and unlikely to remain there very long.

LHP Alexander Wells
MLB Pipeline club ranking: No. 19
2021 Opening Day age: 24

A crafty lefty whose fastball registers in the low-90s, Wells reached Double-A in 2019 but spent all of 2020 in his native Australia, unable to attend the O’s overflow or instructional camps due to the pandemic. But he’s had success at every level, using pinpoint control to overcome a lack of overpowering stuff. The O’s view Wells as internal rotation depth and a potential mid-rotation starter going forward.

INF Rylan Bannon
MLB Pipeline club ranking: No. 25
2021 Opening Day age: 24

Another part of the 2017 package for Machado, Bannon is the only player protected Friday to reach the Triple-A level while with the Orioles. He showed well there in a small sample in 2019, hitting .317/.344/.549 in 20 games, then participated in the O’s overflow and instructional camps in 2020. Bannon is a third baseman by trade but can play second and fill in at short; the real upside is in the on-base and power potential he brings from the right side of the plate. He should get a long look in Spring Training and a legitimate chance to make the team out of camp.

RHP Isaac Mattson
MLB Pipeline club ranking: Unranked
2021 Opening Day Age: 25

The only player acquired by Elias on this list, Mattson arrived from the Angels as part of the return package for Dylan Bundy last winter. He posted huge strikeout numbers in the Angels’ system, reaching Triple-A in 2019 and then turned heads at the Orioles’ overflow camp this summer. Mattson could be part of the O’s bullpen as early as Opening Day.