"It was so cold that day," Parker said. "I couldn't throw anything but fastballs. It was probably less than 40 degrees, half sleet, half rain, and I was just trying to get out of there as soon as I could."
His varsity coach was in no rush, though -- not after seeing Parker pitch. Parker admits he "threw pretty well" that day. Little did he realize it was the start of something special, something that would lead to his name being selected by the D-backs in the first round of the 2007 First-Year Player Draft, something that would eventually prove the key factor in Oakland's offseason decision to trade away All-Star hurler Trevor Cahill.
Parker the pitcher had arrived, years after he had first stepped on a baseball field. Surprisingly, he missed out on T-ball and didn't start playing until he was nearly 7, at which time he was introduced to machine-pitch ball. By age 9, he was playing alongside older brother Justin and 12-year-olds, not once intimidated by their age.
"I think I was so young that it never really registered that I was playing up, and it was never something I thought about until I looked back," he said. "It's something that's helped me, because I try not to overthink things or bring thoughts from the field home with me. I'm able to separate those things and not dwell on anything too long."
Along with Justin, Parker's father, Brent, and late grandfather, Kenton, played significant roles in his development as a player. Kenton served as Parker's first Little League coach, and he was the one who was waiting for the youngster after school with the White Sox game on the television.
As for dad, he and Justin still act as coaches.
"They pushed me more than anyone else," Parker said. "They were, and are to this day, my toughest critics. Obviously they've seen me long enough and they can tell when something's wrong or when my mechanics are out of whack. I'd say they're my personal pitching coaches. We text and call. They know if I want feedback, I'm going to call them first."
Brent was in the stands for his son's first game as a senior at Norwell High School, radar gun handy for the start of a season that would dictate Parker's Draft chances.
Parker tossed three innings before looking over at his father and asking how hard he was throwing. Brent flashed eight fingers, leading Parker to believe he was throwing 88 mph.
"I thought, 'Well, OK, I guess that's all right,' but then he said, 'No, 98.' It didn't even register with me at the time that I was even capable of throwing that hard. I had put in a lot of work in the offseason prior, but I never knew that it would translate into that much more velocity."
That year, Parker went 12-0 with an 0.10 ERA and 116 strikeouts in 70 innings with help from a fastball, slider and changeup. He also hit .481 with nine home runs, en route to being named Indiana Mr. Baseball and garnering an invite to play for the U.S. Junior National Team that won the World Championships in Cuba.
Along came a scholarship from Georgia Tech, which Parker politely turned down when he received the invite he was looking for all along.
"We thought if I was drafted in a position to where I'd be fairly treated, we would think about it," he said. "Obviously, going in the first round, it's a pretty easy decision, to pass up a college scholarship and go play pro ball."
At low Class A South Bend the following year, Parker tallied 117 strikeouts in 117 2/3 innings. He was an All-Star, an honor he received again in 2009 while with Double-A Mobile, where he was promoted after making just four starts with Class A Visalia. But his season ended abruptly at the end of July, when he made his final start of the year before learning he needed Tommy John surgery.
That wasn't the news the D-backs wanted to hear from their top prospect, but Parker insists he wasn't "bitter" about it, as he turned the rehab process into a pivotal time of educating himself on the importance of scouting reports, game plans and workouts between starts -- all of which he had taken advantage of before succumbing to injury. In fact, Parker now calls the surgery "a blessing."
The new version of Parker the pitcher is efficient. He's more concerned with outs than strikeouts, a mindset that has him throwing more for contact in an effort to pitch deeper in games. A newly developed two-seamer, founded midseason last year and deemed by Parker as his "equalizer," has greatly helped that cause, allowing him to pitch down in the zone. Improved grips on his changeup have also aided the 23-year-old, who has compiled a 2.10 ERA in four starts with the A's this year.
"There's a reason we traded one of baseball's best pitchers for him," manager Bob Melvin said. "We've always envisioned him being a frontline starter, especially with the stuff he has, and what we've seen from him is what we expected."