Ellis, who was injured in a nasty collision with Crosby in the final days of Spring Training last year, expects to be healthy by the time Oakland's position players report to Phoenix on Feb. 23.
So certain of Crosby's long-term presence are the A's that top prospect Omar Quintanilla, who shined in the 2004 Arizona Fall League, will begin working out at second base this spring.
"There's no part of my game that I can't improve on," Crosby said earlier this winter. "I think I can get better across the board."
Crosby is particularly intent on increasing his on-base percentage, which was a modest .319 last season.
Beane has often said that the A's can't afford to count on Ellis being 100 percent by Opening Day.