In a move unprecedented in Pennsylvania Ballet's 53-year history, nearly 40 percent of the dancers will be replaced for the 2016-17 season, artistic director Angel Corella said Monday.

Of 43 dancers, 12 were let go and five are leaving on their own. Others, dancers say, are thinking of leaving.

Pennsylvania Ballet, like most ballet companies, offers dancers one-year contracts. The rosters are always in flux, but it is less common to replace so many dancers at once.

"It's always a difficult process for everyone" when contracts are not renewed, Corella said. "It's the hardest part of being an artistic director."

Born in Madrid, Corella, 40, is an international ballet superstar. He was a principal dancer at American Ballet Theatre, where he danced for 17 years. He has been a guest artist with the world's most prestigious companies, including the Royal Ballet, the Mariinsky, and New York City Ballet.

He previously ran his own company in Spain, the Barcelona Ballet. That company has been shuttered, but his sister Carmen, who also danced with ABT, runs the remaining school. He was hired as artistic director of Pennsylvania Ballet in 2014.

This is the first time Corella has been officially allowed to reconsider contracts at the Pennsylvania Ballet. According to the dancers' union, the American Guild of Musical Artists, a new director may let dancers go only after he or she has spent one continuous year on the job. Corella started a few days into the 2014-15 year, so 2015-16 is his first continuous year. Dancers say six others were paid to leave last year.

The reasons Corella gave that contracts were not renewed included: Dancers were not chosen by choreographers for new ballets; dancers were able to dance only certain styles; dancers had trouble adjusting to the new leadership; dancers were of a height that made partnering a challenge.

Of the principal dancers, Francis Veyette, 35, and Brooke Moore, 34, were listed as retiring. But both said they were let go.

"I decided to retire after Angel didn't renew my contract for next season," Veyette said. "I'm too old and broken to try and get a job with another company, but was hoping to dance one more year. Maybe I would have decided to retire this season anyway, but that wasn't my choice."

Veyette's wife, Lauren Fadeley, chose to leave as well. She will join Miami City Ballet as a soloist. Veyette is also the artistic director of Pennsylvania Ballet II, the preprofessional company for young dancers, but he chose to leave that position. Corella will take leadership of that company as well.

Moore was said to be retiring because of foot problems, but she said that was not entirely accurate. She is recovering from ankle surgery, and her contract runs until June 12, but she chose to leave this week and will not have a final performance.

"I am retiring from ballet because of my ankle, but I am leaving Pennsylvania Ballet because I was let go," said Moore, who is also the dancers' union representative.

Moore said that when Corella came, "the environment change was very drastic," and it was rough on many of the dancers hired by the previous artistic director, Roy Kaiser. "We knew that with change comes change. That's inevitable. But it is not Pennsylvania Ballet to us anymore."

She described "an extreme divide" between the old and new guard. Corella "wants to completely change Pennsylvania Ballet," she said. "That's his vision. But for most of us, it doesn't sit well." Moore is moving to Ohio this year to be with her boyfriend and go back to school.

Soloist Evelyn Kocak also will leave the company. "I was let go, which I actually found out that he was planning to do," Kocak said. "It was before this season had even begun. The casting went up for the first program, and I wasn't cast for anything, which had never happened before."

When Corella arrived, she said, "he gave me some nice opportunities. I was really surprised that things had taken that turn.

"Angel's stock answer is that certain people haven't been on board," said Kocak, who plans to move to New York and freelance. "A job in ballet is pretty precious. You have so little time to dance. Even if people have reservations, nobody would want to lose their job. Everybody was giving it a chance. Nobody was challenging him in that way."

There are even fewer jobs now for dancers across the country, since Silicon Valley Ballet in California shut down in March. It's also transition time for the Washington Ballet, as Corella's former ABT colleague Julie Kent took over as artistic director in March.

Kocak and Moore said that while Pennsylvania Ballet, considered a Balanchine company, still dances the great master's works, Balanchine-style dancing is not appreciated in other ballets.

"There are so many ways of doing a step," Moore said. "When you are told, 'That's old-fashioned,' the atmosphere is really negative."

Most of the dancers leaving are from the corps de ballet. They will be replaced from the apprentice program and from outside. Apprentices moving up include Aaron Anker, Peter Weil, Kathryn Manger, and Marjorie Feiring, the first dancer from the School of Pennsylvania Ballet to join the main company.

Of the promotions announced, soloists Lillian DiPiazza, Oksana Maslova, and Mayara Piñeiro will be promoted to principal dancer.

Joining the company as a principal dancer is Sterling Baca, a corps de ballet member in ABT, named by Dance Magazine in December one of 25 to Watch. Sara Michelle Murawski - whom the Inquirer wrote about in 2008, when she was a 16-year-old student at the Rock School for Dance Education - will also join as a principal, from the Slovak National Ballet, where she is a soloist. Dayesi Torriente, a former principal dancer at the Ballet Nacional de Cuba and the fiancee of principal dancer Arián Molina Soca, will be hired as a new soloist.

New corps members from the outside include:

Yuka Iseda, from Japan, who danced Swan Lake with Corella in his previous company, Barcelona Ballet.

Nayara Lopes, from Dance Theatre of Harlem via Brazil, also one of Dance Magazine's 25 to Watch.

Albert Gordon, from Boston Ballet.

Alex Babayev, a former Pennsylvania Ballet II dancer performing in Russia's Stanislavsky Ballet.

Jack Thomas, of Houston Ballet II, who was a finalist at the Prix de Lausanne.

Dominic Ballard, an Australian dancer performing with Murawski in the Slovak National Ballet.