Joe Patterson led the Cadets to a 7-4 record this fall, which included a win over then-No. 1 Gonzaga. (John McDonnell/The Washington Post)

Joe Patterson was fired as head coach of the St. John’s football team after 12 seasons and replaced by Cadets associate head coach/offensive coordinator Joe Casamento, the school announced Wednesday.

The move comes one month after the Cadets’ season ended in the Washington Catholic Athletic Conference playoffs and almost a year after Casamento was brought on board following a stellar 17-year run at Christian Brothers Academy in New York.

“It was the right time to make this change for the future of St. John’s’ football program,” Athletic Director Brian Griffin wrote in an email to The Washington Post. “Joe Patterson helped build a solid foundation, and we are grateful for his dedication. Joe Casamento brings a wealth of experience and an outstanding record to St. John’s, and during the past year it became clear that Coach Casamento is the right man for this job.”

Patterson, 40, will remain on staff at the Northwest school as an English teacher while Casamento will continue serving as the director of the new Entrepreneurial Center for Innovation and Learning at St. John’s.

Casamento, 68, brings more than 40 years of coaching to the helm, with his most notable stint coming at CBA, where he compiled a record of 143-27 and won a New York state title. In January, Casamento was hired to be associate head coach and offensive coordinator at St. John’s following an aggressive recruitment by school officials and alumnus Kevin Plank, the CEO of Under Armour, according to a report by the Post-Standard in Syracuse.

“The vision for excellence here at St. John’s is fantastic, and I’m excited to be a part of it,” Casamento said in the school’s statement. He was unavailable to comment Thursday.

St. John’s players learned the news in a Tuesday meeting with Griffin and Casamento. Many, including junior running back and linebacker Ryan Vessels, came away stunned by the sudden termination of the coach who recruited them.

“It’s devastating. Coach Casamento was a good addition to our coaching staff last year, and there were some feelings that something may happen in the future, but I don’t think any of us expected it to happen so soon,” Vessels said. “Coach Patterson is a great guy, a great coach, and to think he won’t be there for my senior year is tragic, almost. We all felt like we lost a part of us because we were connected to Coach Patterson in a special way.”

During his tenure as head coach, Patterson, a St. John’s graduate, built a record of 76-54 with 10 WCAC playoff appearances, eight winning seasons and a trip to the 2013 conference title game. In Patterson’s final season, the Cadets went 7-4, including a win over rival and then-No. 1 Gonzaga that secured a postseason berth. They eventually fell to eventual champion DeMatha.

“I’ve been overwhelmed by the support I’ve received over the past 24 hours, and I look back on my tenure at St. John’s with tremendous appreciation for the relationships,” Patterson wrote in an email to The Post.

“I’m proud of the effort the players put forth over the years, and I’m proud of the way they carried themselves on and off the field.”