PHOENIX (AP) -- Jarrod Parker is on his way to the minors after a wild outing against his former team.
Manny Ramirez could be headed for a big role with the Oakland Athletics .
The 39-year-old slugger hit a mammoth homer and the A's beat Arizona 6-5 on Monday even though Parker walked seven Diamondbacks batters.
Parker was reassigned to minor league camp after the game. A top prospect, the right-hander was acquired by Oakland from Arizona this offseason in a trade for All-Star starter Trevor Cahill .
Drafted ninth overall by the Diamondbacks in 2007, Parker had Tommy John surgery late in 2009 and missed all of the 2010 season. He admitted he was a bit nervous facing his old team for the first time.
"I feel like I was guiding the ball, trying to be too fine," he said.
Parker gave up one hit and two earned runs in 3 2-3 innings. He did not have a strikeout but was helped by two double plays.
"Give him credit. He made some good pitches when it counted," Diamondbacks manager Kirk Gibson said.
Still, Parker acknowledged the performance was "kind of a step back," and he found out just how far back when he received the news of his demotion from manager Bob Melvin .
The A's, who open the regular season in Japan against the Seattle Mariners next week, do not need a fifth starter until mid-April and it is conceivable that the 23-year-old Parker could return at that point.
"The guys welcomed me. I am in a great situation. I feel pretty good and I am healthy," Parker said.
Melvin was in the Arizona organization while Parker was coming up. He knows Parker is disappointed by the turn of events, but remains optimistic about his future.
"Command of the breaking ball is usually the last to come after Tommy John ," Melvin said. "You have to trust it.
"Today, he was a little excited out there. His stuff is good when he gets it over the plate. He has the stuff to get guys when he gets behind in the count, but you don't want to put guys on base."
Josh Reddick and Brandon Allen also homered for the A's.
Reddick hit a three-run shot in the first and Ramirez highlighted a two-run third by hitting a drive off the center-field batter's eye, about 430 feet away.
Allen, another former Arizona player, connected in the fourth.
If Ramirez remains with the A's, he will have to sit out the first 50 games of the season due to a violation of Major League Baseball's drug policy. He retired last April, but signed a minor league contract with Oakland on Feb. 20.
Ramirez is 3 for 18 with two homers in Cactus League play. Melvin hopes to see what Ramirez can do in games that count.
"He has been showing much better, particularly with the limited number of at-bats he's gotten," the manager said. "We can envision him in the middle of the order."
Arizona right-hander Josh Collmenter struggled through three innings, giving up five runs and six hits - including the homers by Reddick and Ramirez.
"His ball was up. He's unable to get it where he wants it right now," Gibson said. "We shut him down early, and he's a little behind. He'll be fine."
Collmenter was 10-10 with a 3.38 ERA last year.
Cody Ransom hit a two-run homer in the eighth for the Diamondbacks and Paul Goldschmidt had a solo shot in the ninth.
NOTES: Oakland made other roster moves as well, optioning catcher Derek Norris to Triple-A Sacramento and reassigning catcher Ryan Ortiz and outfielders Jeff Fiorentino and Brandon Moss to minor league camp. ... Former Diamondbacks outfielder Colin Cowgill had two hits for the A's, raising his spring average to .436. ... Melvin expects veteran Coco Crisp to move over from center and be his everyday left fielder, with Cuban import Yoenis Cespedes in center and Reddick in right.