CHICAGO -- There are holes to fill in the Cubs' rotation for next season, but the team also has to strengthen its depth behind the Major League staff. That made protecting Cory Abbott from the Rule 5 Draft process an easy decision for the North Siders.

The Cubs selected the contracts of Abbott, infielder Christopher Morel and righty Keegan Thompson on Friday night, adding the trio to their 40-man roster. That effectively removed them from the pool of players eligible for selection in the Rule 5 Draft on Dec. 10. The Cubs' roster now includes 37 players.

It costs $100,000 make a Rule 5 selection, and the player must remain on the MLB roster all season or be offered back to his original team for $50,000.

This offseason, the Cubs have three starters from their 2020 rotation -- Jon Lester, Tyler Chatwood and José Quintana -- on the free-agent market. As things currently stand, Chicago's starting staff includes Yu Darvish, Kyle Hendricks and Alec Mills, with prospect Adbert Alzolay in position to claim a fourth spot.

While the Cubs will be pursuing MLB rotation help this winter, the situation could open opportunities for some internal arms. Top prospect Brailyn Marquez, who was added to the roster in September for his MLB debut, could knock on the door on the big leagues again in 2021. Abbott will also be among the prospects aiming to reach The Show next year.

Here is a round-up of Friday's moves for the Cubs.

Added to the 40-man roster

Abbott (No. 12 on the Cubs' Top 30 Prospects, per MLB Pipeline)
The 25-year-old Abbott spent time in 2020 at the Cubs' alternate training site in South Bend, Ind., and reported to instructional league after the season. The right-hander is poised to serve as Major League rotation depth as soon as '21, depending on the needs next year and how this offseason plays out.

Abbott, who was picked in the second round of the 2017 MLB Draft, made 26 starts for Double-A Tennessee in '19. He logged a 3.01 ERA with 166 strikeouts against 52 walks in 146 1/3 innings. In three pro seasons (excluding '20), Abbott has a 2.84 ERA with 10.3 strikeouts per nine innings and a 3.4 strikeout-to-walk ratio.

Morel (No. 11)
Morel made a brief appearance at Wrigley Field during Summer Camp in July, delivering a double that ignited a three-run rally. Talk about making a good impression. The 21-year-old infielder is versatile and a strong defender at third base, and he also has experience at short along with limited action in the outfield.

In 73 games with Class A South Bend in 2019, Morel hit .284 with six homers, seven triples, 15 doubles and 31 RBIs. Signed out of the Dominican Republic in August of '15, Morel got experience at the Cubs' South Bend training site in '20.

Thompson (No. 26)
A third-round pick out of Auburn in the 2017 MLB Draft, Thompson spent part of the '20 season at Chicago's alternate training site in South Bend as part of the 60-man pool. Injuries limited the righty to 10 Minor League innings in '19, though he struck out 26 while walking six in 25 1/3 innings in the Arizona Fall League later that year. In '18, Thompson posted a 3.61 ERA with 115 strikeouts and 34 walks in 129 2/3 innings between Class A Advanced Myrtle Beach and Double-A Tennessee.

Top prospects left unprotected

Strictly looking at the MLB Pipeline's Top 30 Prospects list for the Cubs, left-hander Brendon Little (No. 30) was the lone eligible player left unprotected for possible selection in the Rule 5 Draft.

• Gauging the state of the Cubs' farm system

The 24-year-old Little was a first-round pick (No. 27 overall) by the Cubs in the 2017 MLB Draft. In '19, he topped out at Class A Advanced Myrtle Beach among three stops. In 55 1/3 innings overall, the lefty had 57 strikeouts, 26 walks and a 3.58 ERA.

Other names of note

Right-hander Trevor Megill (selected by the Cubs in the 2019 Rule 5 Draft) and righty Michael Rucker (selected by the Orioles in '19 and returned to the Cubs) spent time at the South Bend site in '20. Neither are on the 40-man roster, leaving them exposed to the Rule 5 process again.

Catcher P.J. Higgins has been in big league camp in Spring Training multiple times for the Cubs and served as the primary fourth-string backstop in 2020. He had an .895 OPS in 36 games with Triple-A Iowa in '19, and he was at the South Bend camp in '20 following Summer Camp.

Right-hander Dakota Mekkes (10th round of the 2016 MLB Draft out of Michigan State) spent the '20 season at the South Bend site and has been in big league camp the past two years. The 6-foot-8 righty has struck out 11.5 batters per nine innings in four pro seasons with Chicago (excluding '20).