SAN DIEGO -- The Padres entered Friday with an open spot on their 40-man roster and MacKenzie Gore needing to be protected from the Rule 5 Draft.

So this much was a foregone conclusion: The Padres officially added Gore, their top pitching prospect, to the 40-man roster on Friday afternoon.

But the roster shuffling didn't end there. San Diego added three other prospects to its 40-man roster ahead of the deadline to protect players from the Rule 5 Draft. Here's the full list of additions:

• LHP MacKenzie Gore (No. 4 Padres prospect, per MLB Pipeline)
• IF Eguy Rosario (No. 15)
• RHP Steven Wilson (No. 21)
• RHP Efraín Contreras (No. 23)

To clear space for Wilson, Contreras and Rosario, the Padres outrighted right-hander Reggie Lawson and outfielder Jorge Oña to Triple-A El Paso. Meanwhile, right-hander Shaun Anderson, who had a 5.79 ERA in five Padres outings last season, was claimed off waivers by Toronto.

The Rule 5 Draft -- in which teams select prospects from other organizations but must keep them on their big league roster all season -- is scheduled to take place on Dec. 8. This year's class of eligible players includes most college players drafted in 2018 or earlier and most high school/international players signed in 2017 or earlier. Teams can protect those players by adding them to their 40-man rosters.

Gore, of course, is the headliner of this group. Once the sport's top pitching prospect, he struggled over the past two seasons. But the Padres like the progress he made in the season's final two months.

Gore spent time at the team's complex in Peoria, Ariz., recovering from blister issues and working through some mechanical kinks. After his return, he posted a 2.67 ERA across six Minor League starts (mostly at lower levels). Then, he struggled a bit in three Arizona Fall League outings with a 6.35 ERA.

"He's back throwing the ball well from a stuff standpoint," Padres general manager A.J. Preller said last week at the GM Meetings. "Velocity and quality of his pitches -- that was a big positive for us.

"But he'll be the first to tell you he's still got to tighten up on a few things from a command standpoint. Just get a little bit sharper overall with some of his secondary pitches and his fastball command. But it was fun seeing him back out there. He had some dominant moments. Now we've got to make that more consistent."

If the Padres can harness that consistency out of Gore, they envision him as an important rotation piece on their 2022 roster. Pitching is Preller's top priority this winter, but he's also been quick to note that the team might have a number of solutions in-house -- including Gore.

To that end, Gore spent time at Petco Park this month working with new pitching coach Ruben Niebla.

"That was kind of the last step for him in this season," Preller said. "It's been a long year for him. Now he'll get on an offseason-type program."

Gore isn't the only impact arm the Padres felt they needed to protect -- as evidenced by their decisions on Friday.

Wilson, 27, has allowed two hits and no walks while striking out 11 across seven Dominican Winter League innings. He could be a factor in the Padres' bullpen mix next season. And keep an eye on Contreras, who team decision-makers are quite fond of.

The 21-year-old right-hander missed the past two seasons due to Tommy John surgery. But he has turned heads with an excellent curve, a solid changeup and an ability to fill up the strike zone. If he continues his current trajectory, Contreras could serve as a useful depth piece next season, perhaps even earning a big league breakthrough.

As for Rosario, he batted .281/.360/.455 for Double-A San Antonio last season, splitting time between second, third and short.

Perhaps the most notable Padre left exposed to the Rule 5 Draft was 21-year-old catcher Brandon Valenzuela, the team's No. 19 prospect. The Padres remain high on Valenzuela, but he likely has a couple of years of seasoning left before he's big league ready. As such, they'll hope for the possibility that 29 other teams pass on him next month.