A full 40-man roster means the Royals are virtually certain to make some personnel moves prior to Tuesday’s deadline for filing reserve lists in order to prevent some of their top prospects from being eligible for selection in next month’s Rule 5 Draft.

Two likely additions stand out: left-handed pitchers John Lamb and Mike Montgomery. While both suffered setbacks over the last two years — Lamb underwent elbow surgery; Montgomery battled ineffectiveness — the Royals are unlikely to leave either unprotected.

Anybody else?

“You’ve just got to manage it,” general manager Dayton Moore said. “You want as much flexibility as possible, but we know we’re not going to be able to protect everybody we want to protect.

“We’ll protect as many guys as we can and save room for anybody who upgrades us.”

Outfielder Wil Myers, the Royals’ top prospect, isn’t yet Rule 5 eligible and therefore doesn’t require protection. That was a major reason the club chose not to promote him at the end of last season — doing so would have required that he be added to the roster.

The reserve lists cover an organization’s major- and minor-league teams, but the biggest impact, typically, is the pool of players created for the Rule 5 Draft. The intent is to allow players blocked in one system to reach the majors in another organization.

Generally, players must be protected — i.e., placed on the 40-man roster — after their fourth or fifth professional season. Those 19 or older when they sign their first contract must be protected after four years; those younger than 19 have a five-year wait.

Players selected in the Rule 5 Draft, at a cost of $50,000, must remain in the majors for the entire following season or be offered back to their former club for $25,000. The draft is Dec. 6 at the Winter Meetings in Nashville, Tenn.

Leaving a pitcher unprotected is typically a bigger risk because clubs often find it more difficult to carry a position player for a full season. In contrast, pitching prospects can serve as long relievers — as the Royals used Nate Adcock in 2011.

Since the Royals have no vacancies on their 40-man roster, any additions prior to the 11 p.m. deadline will require a corresponding space-clearing move. Those likely at risk include first baseman/designated hitter Clint Robinson and outfielder Derrick Robinson.

Lamb, 22, was rated by Baseball America as the No. 18 overall prospect prior to the 2011 season before undergoing Tommy John surgery in June. He made just six appearances after returning last season but is on track for full duty in 2013.

Montgomery, 23, was the No. 19 overall prospect in the pre-2011 rankings but regressed over the last two years. He was demoted late last season from Class AAA Omaha to Class AA Northwest Arkansas.

“It’s hard to explain with Montgomery just because you still see it,” assistant general manager J.J. Picollo said. “What Mike is battling more than anything is just (a lack of) confidence…We’ve got to be patient with him.”

The Royals must also decide whether to protect Chris Dwyer, another left-handed pitcher who has failed to meet expectations. Dwyer, 24, was the No. 83 overall prospect prior to 2011 but is just 16-22 with a 5.74 ERA in 52 starts over the last two years.

Two relievers are likely to get consideration because of strong performances in off-season leagues: lefty Justin Marks and veteran right-hander Juan Gutierrez.

Marks, 24, was 5-1 with a 2.59 ERA in seven starts in the Arizona Fall League. A starter throughout his four professional seasons, he might a better big-league fit as a reliever. He was a combined 3-6 with a 4.50 ERA in 20 games last season at three levels.

The Royals acquired Marks from Oakland with pitcher Vin Mazzaro in the Nov. 10, 2010 trade for outfielder David DeJesus.

Gutierrez, 29, recently re-signed with the Royals as a minor-league free agent. He appeared in 143 games for Arizona from 2009-11 before suffering a shoulder injury. Gutierrez has a 1.50 ERA in 13 games in the Venezuelan Winter League.

More rankings

Myers is No. 1 in Baseball America’s annual ranking of the Royals’ top prospects. The magazine offers its Top 10 in its current issue.

The rest of the Top 10: Kyle Zimmer, Bubba Starling, Yordano Ventura, Jake Odorizzi, Jorge Bonifacio, Adalberto Mondesi, Sam Selman, Orlando Calixte and Jason Adam.

A comparison of how BA’s list compares with other rankings is available on The Star’s Ball Star blog at KansasCity.com.

Winter updates

Catcher Salvy Perez is off to a torrid start at La Guaira in the Venezuela Winter League at nine for 23 with nine RBIs in his first five games. He had two homers and four RBIs in Sunday’s 9-7 loss to Zulia.

Other notables:

• Utility infielders Tony Abreu and Irving Falu are struggling. Abreu is batting .237 (nine for 38) in 11 games for Aguilas in the Dominican Republic, while Falu is at .192 (five for 26) for Mayaguez in Puerto Rico.

• Infielder Christian Colón, in contrast, is batting .343 (12 for 35) for Ponce in Puerto Rico.

• Catcher Manny Piña is still looking for his first winter hit; he is zero for nine in six games for Margarita in Venezuela.

• Right-hander Guillermo Moscoso, acquired recently on waivers, has four straight scoreless one-inning outings for Caracas in Venezuela. Overall, he has allowed one run and three hits in five innings.