OAKLAND -- While the A's evaluate potential roster additions on the outside market, they must also tackle internal homework with an important deadline in mind. By Friday, teams must determine which players they want to protect from next month's Rule 5 Draft.
That includes any player not on the 40-man roster who signed in 2012 at 18 years or younger, or in 2013 at 19 years or older.
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For the A's, assessing their roster immediately began at season's end; they significantly pared down their 40-man roster by eliminating more than a dozen players -- many of whom were on the 60-day disabled list -- and now count 36 ahead of Friday's deadline, leaving four spots for Rule 5-eligible players.
Only a select number of players are selected in the Rule 5 Draft, considering the commitment required of the acquiring team. Players selected must remain on the team's 25-man roster for the entire season or be offered back to their original club.
Still, teams are diligent about deciding whom to protect given the prospect of losing prime talent. Here's a look at A's prospects who will warrant consideration for protection from the Dec. 8 Draft:
SS Franklin Barreto: This is a no-brainer for the A's, who deem Barreto their top prospect. He's also considered close to Major League-ready, having gained an entire season of experience at the Double-A level before being introduced to Triple-A at the conclusion of the 2016 season. The 20-year-old infielder was the key piece to the deal that sent Josh Donaldson to the Blue Jays in 2014.
OF Jaycob Brugman: A 17th-round Draft pick of the A's in 2013, Brugman had a breakout season this year. He earned a promotion to Triple-A Nashville and made good on the decision by batting .295/.352/.438 with 67 RBIs in 94 games for the Sounds. The A's are already short on outfielders, so the addition of Brugman, who can play all three outfield positions, to the 40-man roster would make sense for more than one reason. Otherwise, he could easily be plucked out of the Rule 5 Draft if left unprotected.

SS Yairo Munoz: Ranked by MLB Pipeline as the A's No. 7 prospect, Munoz brims with raw talent, which the A's will have to take into consideration despite having watched him struggle to the tune of a .240 average and .298 on-base percentage in his first season at Double-A. The 21-year-old Dominican has above-average power, along with a versatile skillset in the infield that makes him a prime asset.
RHP Paul Blackburn: Blackburn was the lone player the A's received from Seattle in exchange for veteran Danny Valencia last week. It was the second trade of the year for the 22-year-old right-hander, who came over to the Mariners from the Cubs midseason in the Mike Montgomery deal. He finished the season with a 3.27 ERA across 26 games (25 starts) at the Double-A level.
RHP Dylan Covey: An oblique injury shelved Covey for much of 2016, limiting him to just six starts. He's tried to make up for lost time in the Arizona Fall League, but it's unclear whether that will be enough to convince the A's to add him to the 40-man roster.
RHP Bobby Wahl: The hard-throwing Wahl has been derailed by injuries during his professional career, but he locked down 14 of 15 save opportunities between three levels this year while pitching to a 2.65 ERA with 65 strikeouts in 54 1/3 innings.