The land of opportunity turned into a field of dreams for the kid from Indiana and his new teammates, who merely shocked the baseball establishment by improving by 20 wins and winning the loaded division.
From prospect to respected Major League starter after one sizzling summer, Parker, at 24, is coming off a 13-win season for a 94-win AL West champion.
Parker, who had a 3.47 ERA with 140 strikeouts in 181 1/3 innings in 2012, is the projected ace of one of the best staffs in the game. The talent is clearly there, and so is the makeup. Right, Bob Melvin?
"Yeah, definitely," Melvin, the A's manager, said, without hesitation on Friday before Parker took the mound against the defending World Series-champion, cross-bay Giants in a Cactus League contest.
Parker wasn't with the A's when they opened the 2012 season in Japan against the Mariners. He'd been sent to Triple-A Sacramento to smooth over a few edges.
"He didn't go on the Japan trip, which was very disappointing for him," Melvin, the AL Manager of the Year last season, said. "He starts in the Minor Leagues, and next thing you know, he was starting Game 1 in the playoffs. The ability, we knew it was there. He had to refine some things in Spring Training."
It seemed to happen almost that fast. One day he's dealing in the Pacific Coast League, the next day Parker is in Oakland, hanging up goose eggs for a team that unleashed a furious finishing kick and pushed Texas into a Wild Card game it lost to the Orioles.
Justin Verlander brought the curtain down on the A's, winning Games 1 and 5 of the AL Division Series against Parker. While reality ultimately intervened, just being there was the point for the young pitcher and his team.
"Starting the season in the Minor Leagues and pitching Game 1 of the playoffs, that was very gratifying," Parker said. "It's pretty impressive what we were able to do as a staff.
"It was kind of a reward for the work we put in, grinding it out during days in the middle of the year when we were going through a rough patch. We could have gone the opposite way, but we put ourselves in a position to win in the last week and got it done.
"To be able to look back at last year as a whole, what's impressive was the whole team effort."
A's general manager Billy Beane resisted parting with his young arms, in high demand over the winter. But he did add several quality players.
Chris Young, another D-backs import, is a brilliant defensive center fielder with pop. Catcher John Jaso brings experience defensively and the ability to get on base for an offense built on power.
To replace Cliff Pennington, dispatched to Arizona in the Young swap, Beane landed a pair of shortstops: Jed Lowrie from the Astros and Hiroyuki Nakajima from Japan. Lowrie could end up at second.
The outfield is deep and potentially great with gifted Yoenis Cespedes, Josh Reddick, Coco Crisp, Young and Seth Smith.
If he can stay healthy and appear in more than the 129 games he played as a newcomer to all things American, Cespedes has MVP potential. The Cuban comet has a power/speed combination matched by the Angels' Mike Trout and very few others.
The mission for the A's is to do it again in the face of the inevitable skepticism -- and maybe even do it a little better. Parker figures to be at the forefront, from Day 1 this time.
"Throughout baseball," Parker said, "the game starts with your starting staff. In successful ones, you become close friends and competitors as well. You have a chance to one-up each other. This is only our second spring together, but it's something that's developing."
Bartolo Colon and Brett Anderson are more experienced arms, but Parker and Tommy Milone were the rocks in the rotation in 2012, becoming the first rookie teammates to win at least 13 games each since the 1952 Brooklyn Dodgers.
They're complementary in every respect, a blueprint for any rotation anchors: Parker a righty with high-powered stuff, Milone a clever lefty; Parker engagingly confident, Milone equally confident but in a more reserved fashion.
A.J. Griffin, Dan Straily and Travis Blackley also took advantage of the opportunities created by the absences of Colon, Anderson and Brandon McCarthy last year to form an all-freshman rotation for a stretch while the A's were tracking down the two-time league champion Rangers. A's rookies won a record 54 games.
In his fifth professional season -- he missed 2010 with Tommy John surgery -- Parker has the look of a guy who will be making All-Star teams for years to come.
"I never want anything handed to me," said Parker. "I've always worked for it and competed. You're always focused on getting better. It starts in the offseason, to be ready when you get here, so you can let what you do on the field take care of itself."
Parker and his friends look capable of making more East Bay magic in 2013.