The A's on Friday, facing a deadline to finalize their 40-man roster, added five players to the list so as to protect them from being exposed to the upcoming Rule 5 Draft at the annual Winter Meetings.

Oakland selected outfielders Michael Taylor and Corey Brown and infielders Adrian Cardenas and Sean Doolittle from Triple-A Sacramento, as well as recently acquired right-hander Trystan Magnuson from Double-A Midland. By doing so, the A's have reached their limit on the 40-man roster.

Taylor, Brown, Cardenas, Doolittle and Magnuson are now all shielded from the Rule 5 Draft, which exposes players not on the 40-man roster to other teams. Anyone signed when they were 19 or older who has spent three full seasons in the organization, as well as anyone signed at 18 or older who has spent four full seasons in the organization, is eligible to be selected if they are not on their organization's 40-man roster.

The selected players must be kept on the selecting team's 25-man big league roster out of Spring Training or be offered back to the original club for half the selection price, or $25,000. Several teams choose not to make Rule 5 selections, but the A's are often involved, as they were last year when they chose reliever Bobby Cassevah before returning him to the Angels.

Teams must have room on their 40-man roster to partake in the Draft, and the A's are expected to have slots open by Draft day (Dec. 9) following the Dec. 2 non-tender deadline. Jack Cust is a strong non-tender candidate, as is Travis Buck. Other possibilities include Kevin Kouzmanoff, Edwin Encarnacion and Conor Jackson.

Taylor represents perhaps the most prized roster possession, as he is currently pegged the team's top prospect now that Chris Carter has made it to the Majors. He compiled a .272 average with 26 doubles, six triples, six home runs and 78 RBIs, along with 16 stolen bases in 127 games for Triple-A Sacramento this past season. He often struggled to find consistency at the plate, though, and is now facing a crowded Oakland outfield picture, so it's likely Taylor will again start the year in Sacramento.

Brown and Cardenas both split the 2010 season between Midland and Sacramento. The former hit .320 with 10 home runs, 49 RBIs and 19 stolen bases in 90 games for the RockHounds and earned Midseason and Postseason All-Star honors. The outfielder endured a rough stretch at Sacramento, batting 193 in 41 games, but then went 3-for-11 with a double and two RBIs in four playoff games for the River Cats.

Cardenas, meanwhile, finished the 2010 season as the fourth-leading hitter in the A's farm system with a combined .304 average. He hit .345 with three homers and 32 RBIs in only 51 games with Midland before moving on to Sacramento, where he batted .267 with one home run and 21 RBIs in 58 contests. Cardenas, 23, is expected to battle Jemile Weeks for a future at second base in Oakland.

Doolittle, often considered one of the organization's most promising prospects, has somewhat lost that label due to knee injuries the past two years. He missed the entire 2010 season while rehabbing a second knee surgery performed in July but is expected to try for a healthy 2011 campaign. He was limited to 28 games in 2009 following a 2008 season that saw him lead the A's farm system in hits (153) and doubles (40) while also ranking third in RBIs (91), fourth in walks (63) and fifth in home runs (22).

As expected, a roster spot went to Magnuson, who was acquired along with fellow right-handed reliever Daniel Farquhar from the Blue Jays in exchange for Rajai Davis on Wednesday. Magnuson, 25, was 3-0 with a 2.58 ERA and five saves in 46 appearances for Double-A New Hampshire this season. The 6-foot-7 righty is believed to be near Major League-ready.