The Oakland Athletics added Triple-A Sacramento players Grant Green, Shane Peterson and Arnold Leon, along with pitcher Michael Ynoa from Single-A Vermont, to their 40-man roster on Wednesday, according to CSN Bay Area. The additions don't allude to the foursome playing for Oakland this upcoming season so much as they tell of the Athletics' wish to hang on to the prospects.

The move protects the four prospects from being taken by another MLB team in the Rule 5 Draft set for Dec. 6.

Under Rule 5 regulations, younger players under certain eligibility rules can be selected by another team, which must pay $50,000 for the prospects. The selected players must be on the active roster of their new team and off the disabled list for a minimum of 90 days. Otherwise, the team that lost the prospect could pay $25,000 to regain their player.

If that offer is rejected, the player can be waived.

Oakland cleared space by designating infielder Brandon Hicks and reliever Jim Miller for assignment, and sending Andrew Carignan to Triple-A.