Pedroia, 35, has not suffered any setbacks in his recovery from a lingering knee injury but is being shelved out of caution so he can continue to build up strength, according to Alex Speier of The Boston Globe.
"He understands," Cora said. "Obviously a little down - which is great. It means he's feeling good."
Pedroia feels so good, in fact, that he doesn't quite agree with the decision to extend his absence.
"I'm ready for Opening Day," Pedroia told Bradford. "They're scared. No one has ever come back from something like this."
A fixture of the Red Sox for years, the four-time All-Star appeared in only three games in 2018. There is no timeline for his activation.
Boston will enter the season with 13 pitchers on the roster instead of 12 had Pedroia been at full health, according to Jen McCaffrey of The Athletic.