The first reaction among the Royals was surprise Wednesday afternoon upon learning former teammate Melky Cabrera, now a member of the San Francisco Giants, had received a 50-game suspension after testing positive for a performance-enhancing substance.

“Everyone heard the news once we got to the clubhouse,” left fielder Alex Gordon said. “He was always a hard worker and always gave 100 percent. We’re all disappointed, because he was having such a great year. We were all pulling for him.”

Cabrera’s suspension is effective immediately and halts the best season of his eight-year career. He was batting .346 with 11 homers and 60 RBIs while leading the National League with 84 runs and 159 hits.

“You just hate to see something like that happen,” right fielder Jeff Francoeur said, “but we do have a test, and he’s already come out and apologized and admitted he did it. Obviously, he’s not fighting it. He’s not trying to deny it.”

Cabrera, 28, tested positive for testosterone, a banned substance under Major League Baseball’s Joint Drug Prevention and Treatment Program. The suspension will cover the remainder of the Giants’ season, 45 games, and carry into the postseason or next year.

“My positive test was the result of my use of a substance I should not have used,” Cabrera said in a news release issued by the players union. “I accept my suspension under the Joint Drug Program, and I will try to move on with my life.

“I am deeply sorry for my mistake and I apologize to my teammates, to the San Francisco Giants organization and to the fans for letting them down.”

Cabrera was initially in the lineup for Wednesday’s game against Washington. The Giants also issued a news release after the commissioner’s office announced the suspension:

“We were extremely disappointed to learn of the suspension of Melky Cabrera for violating Major League Baseball’s Joint Drug Prevention and Treatment Program. We fully support Major League Baseball’s policy and its efforts to eliminate performance enhancing drugs from our game.

“Per the protocol outlined by Major League Baseball’s collective bargaining agreement, the Giants will not comment further on this matter.”

Cabrera is a pending free agent who resurrected his career last year with the Royals, who signed him in December 2010 after he became a free agent following his release by the Atlanta Braves.

Royals officials said they have no reason to suspect Cabrera violated the policy last season. General manager Dayton Moore said: “He was tested. Just like everybody else.”

Testosterone is classified as a steroid by the sport’s drug policy and a first failed test calls for an immediate 50-game suspension. Cabrera vehemently denied failing a drug test last month when allegations began circulating.

Cabrera combined last year with Gordon and Francoeur to provide the Royals with the most productive outfield in either league. The three threw out 49 runners while batting a combined .295 and averaging 72 extra-base hits, 99 runs and 91 RBIs.

“You go around to guys in this clubhouse and ask anybody,” Francoeur said. “He was a great teammate, and is a great guy. You never want to judge what a guy is thinking, but I know he knows he messed up.”

The Royals traded Cabrera to the Giants on Nov. 7, 2011, after failing to reach agreement on a multiyear extension. The Royals received left-handed pitchers Jonathan Sánchez and Ryan Verdugo in return.

That trade became a disaster for the Royals when Sánchez went 1-6 with a 7.76 ERA in 12 starts. He was designated for assignment on July 17 — three days before the Royals traded him to Colorado for veteran right-hander Jeremy Guthrie.

In contrast, Cabrera was voted a starter for the All-Star Game and made a triumphant return last month to Kauffman Stadium, being picked as the game’s most valuable player.

“I’m just disappointed for him,” Francoeur said, “because all of us in here pulled so much for him this year. Gordo and myself, being in the outfield last year with him, were so proud to see him come back here for the All-Star Game and hit the home run.”