Major league teams have until 8 p.m. on Monday to set their 40-man rosters ahead of the Rule 5 draft on Dec. 14.
The Red Sox have three spots open on the 40-man roster and could well use them all to maintain their rights to some veteran minor leaguers.
The top candidates to be protected are lefthander Jalen Beeks, righthander Chandler Shepherd, and righthander Jake Cosart.
Beeks, 24, was 11-8 with a 3.54 ERA last season in 26 starts for Double A Portland and Triple A Pawtucket. He had 155 strikeouts in 145 innings.
Shepherd impressed in spring training last year but had a 4.07 ERA for Pawtucket. He did average 10.3 strikeouts per nine innings, however. Shepherd is playing winter ball in Mexico and working as a starter. He is 3-2 with a 4.09 ERA in seven games.
Cosart, 23, was a third-round pick in 2014. He was 5-2 with a 3.10 ERA pitching in relief for Portland.
Righthander Ty Buttrey, a fourth-round pick in 2012, is another possibility. But he was hit hard last season after being shifted to the bullpen. Buttrey had a 4.81 ERA and 1.46 WHIP for Portland and Pawtucket.
Buttrey improved at the Arizona Fall League, posting a 2.16 ERA in seven relief appearances.
Almost sure to be left unprotected is lefthander Trey Ball, the seventh overall pick of the 2013 draft. He is 29-42 with a 4.67 ERA over five seasons after being signed to a $2.75 million bonus.