STANFORD, Calif. — Almost a week after signing day, Stanford might have landed its biggest addition heading into next season.

The school announced Monday that Tyler Gaffney is leaving professional baseball to make a surprise return to the football team. After a year of playing in the minors for the State College Spikes, Gaffney will rejoin the Cardinal for the second half of spring practices when he enrolls in classes again April 1.

“As I have grown and matured over the past year, I have come to realize how much I missed my football family at Stanford and how much I missed the game of football,” Gaffney said in a statement.

Gaffney called it the “ideal time” to return to Stanford, which won the Pac-12 Conference and Rose Bowl last season. He said he wanted to finish his degree, double majoring in sociology and psychology, and explore his football potential.

The two-sport player also thanked the Pittsburgh Pirates, the Spikes’ parent organization last season, for the opportunity that “permitted me to grow and mature in character.”

“With the benefit of this experience, I will continue to learn about myself and follow the path where my truth will lead me,” he said.

Gaffney’s return should help alleviate the loss of starting running back Stepfan Taylor.

In his junior season, Gaffney ran for 449 yards (6.1 yards per carry) and seven touchdowns and had 79 yards receiving for another TD as Taylor’s backup. He also was the primary ball carrier in the Cardinal’s wildcat formation, which coach David Shaw didn’t use much last season.

The Pirates drafted Gaffney in the 24th round last year. The outfielder batted .297 with a .483 on-base percentage for the Spikes.

Gaffney is the second Stanford player to spurn the Pirates recently. Pittsburgh drafted pitcher Mark Appel eighth overall last year. But Appel was the only unsigned player among 31 first-round picks last year, turning down the Pirates’ $3.8 million offer in the first year of new restrictions designed to slow draft spending. He is a senior at Stanford now.

Gaffney, a San Diego native, hasn’t played college football since Stanford’s overtime loss to Oklahoma State in the Fiesta Bowl on Jan. 2, 2012. While his signing with the Pirates ended his college baseball eligibility, he still maintained his final year of college football eligibility.

Gaffney will compete with Anthony Wilkerson, Remound Wright, Ricky Seale and Barry Sanders for playing time next season.

“I’m very proud of Tyler Gaffney making the decision to come back and finish his degree, while also rejoining the football team,” Shaw said. “Tyler’s first three years at Stanford, he contributed to a lot of big games and a lot of big wins. He will join a talented and diverse group of running backs, which as a unit we believe is as good as any in the nation.”