So much for that security blanket.

The emergence of rookie Greg Bird last season gave the Yankees confidence that they had a more than capable option at first base and a possible replacement long-term for the aging and increasingly injury-prone Mark Teixeira.

No longer. At least, not for 2016.

The Yankees announced Monday afternoon that the 23-year-old first baseman, who posted a .261/.343/.529 slash line with 11 homers in 157 at-bats as a rookie in 2015, will miss the 2016 season because of a torn labrum in his right shoulder. The club said the lefthanded-hitting Bird, a top prospect in the system who quickly became a favorite of Yankees fans after being called up in August, will have surgery Tuesday at the Hospital for Special Surgery.

“Last year we lost a significant piece [Teixeira], and obviously Bird helped cushion that blow,” general manager Brian Cashman said. “There was not a plan for him to be on the 25-man roster this year if we had full health. Hopefully, we have full health. If we have an injury that was long term, he was ready to plug in and play. We don’t have that option now.”

Pitchers often need well more than a year, and sometimes two or more, to completely recover from labrum surgery, but the time frame isn’t as drastic with position players. The organizational expectation is that Bird will be ready by spring training 2017.

Bird was slated to be an option behind Teixeira, who will turn 36 in April, and designated hitter Alex Rodriguez, who will be 41 in July. A completely healthy season for both veterans is unlikely. Cashman said “between now and Opening Day,” securing insurance at first base to stash at Triple-A is a priority. Dustin Ackley currently is Teixeira’s backup on the big-league roster.

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Bird battled shoulder issues most of 2015. He went on the disabled list on May 8 and missed nearly a month with a slight tear in the labrum.

“He returned [from the DL] without complaint and went through his exit physical [after the American League wild-card loss] without complaint,” Cashman said.

But a week after that physical, Cashman said Bird’s agent told him the shoulder had “bothered” him throughout the season.

Bird then was evaluated by team physician Christopher Ahmad and Dr. David Altchek, who will perform the surgery. Both doctors said there didn’t seem to be any change in the tear and recommended rest and strengthening exercises.

But when Bird started “ramping” up his baseball activities, which included workouts at the team’s minor-league complex starting in mid-January, the pain returned. After another MRI, Ahmad “noticed some changes” in the labrum and recommended surgery, Cashman said.