All three players subsequently became free agents.
The loss of Cust and Buck were highly expected, as was the parting of ways with one of the club's two third basemen on the same day rampant reports spread about Adrian Beltre being close to a deal with Oakland. Beltre, however, told the Boston Globe late Thursday that his first preference is returning to the Red Sox.
Encarnacion's departure, which came just 20 days after the A's claimed him off waivers from the Blue Jays, paved the way for the A's to tender incumbent third baseman Kevin Kouzmanoff a contract. What that decision -- choosing a better defensive third baseman over one with more power -- says about the club's pursuit of Beltre is unknown.
Thursday's news marks the second straight year in which the A's have non-tendered Cust, whose exit could signal thinking that Oakland officials feel confident about signing a free agent such as Lance Berkman. A's representatives met with Berkman in Houston on Tuesday and are still considered to be strong suitors. Adam Dunn was also on Oakland's radar, but multiple reports confirmed Thursday he has reached a deal with the White Sox.
Cust, who earned $2.65 million in 2010, would have likely doubled that figure for the 2011 season through arbitration based on recent performance. Last year, the A's wound up agreeing on a one-year deal with the slugger, but the two parties aren't expected to reunite again this time.
The 31-year-old Cust, who managed to compile his best average (.271) since joining the A's in 2007 but saw his home run (13) and RBI (52) totals drop, batted .247 with 97 home runs, 281 RBIs, 377 walks and 673 strikeouts in 533 games during his four years with Oakland.
Buck, meanwhile, endured another injury-plagued season in 2010 and wasn't offered much of a shot in Oakland when healthy. Already expected to be non-tendered months ago, his Super Two status all but ensured Thursday's inevitable news despite Buck once being tagged as one of the franchise's top prospects.
The club's other arbitration-eligible players, which included hurlers Craig Breslow, Dallas Braden, Joey Devine and Brad Ziegler, along with outfielders Conor Jackson and Ryan Sweeney, were all tendered contracts.
By tendering them contracts, the A's now begin the arbitration process, in which the player and club exchange offers on Jan. 18. If the sides can't reach an agreement on a contract, a three-judge arbitration panel will conduct a hearing and assign the player either the club's offer or his offer -- nothing in-between -- as his salary for 2011. The A's, however, have enjoyed great success with avoiding arbitration hearings.