Gonzalez had joined the Phillies as part of the December 2005 trade that sent slugger Jim Thome to the Chicago White Sox.
"I liked everything about him," manager Charlie Manuel gushed that spring. "He's got an idea of where he's going to go - the big leagues."
Reading is where Gonzalez landed that spring, which was still a huge step up for a young lefthander who had made only 13 starts in high-A ball with the White Sox the year before.
"I was 20 years old at the time," Gonzalez recalled before Washington played its final regular-season game against the Phillies last week. "I was a young kid still maturing, and I was with a bunch of very talented ballplayers who had been around and were more mature than I was.
"It was a learning curve. That was a year where I gave up a lot of home runs and a lot of walks. I felt like I was going for the triple crown of all the worst numbers."
It was, in fact, the worst season of his minor-league career. He went 7-12 with a 4.66 ERA. He walked 81 batters and surrendered 24 home runs in 1542/3 innings. His 166 strikeouts, however, were still a clear indication of a kid with a power arm.
"At that point he was a real high-energy guy, almost to the point of being too hyper," said Mike Arbuckle, a former Phillies assistant general manager now working in Kansas City. "We felt like he would take care of his command issues once he calmed down."
Gonzalez believes Reading provided a huge step in his maturation process because it was easy to get flustered in a small ballpark with hitters who were much more experienced.
"It's a beautiful ballpark," he said. "It's actually the most fun I had [in the minors], but you also look at it for what it is. It's a tough ballpark to pitch in. It's one of those places that if you don't keep the ball down and if you make mistakes, they're going to make you pay for it. It's where I learned how to pitch. I think Reading was a great place for me to grow up. That's the best way to put it."
At the time, Phillies general manager Pat Gillick was candid in his evaluation of Gonzalez.
"To be successful, he's going to have to get his emotions under control," Gillick said. "That's his whole thing. Gio is too emotional on the mound. His ability is there. He's got all the pitches. He's a great competitor, but sometimes he gets excited on the mound."
Gonzalez stopped short of saying he was immature, but agreed that he had some growing up to do.
"I'm 27 now . . . and if I could go back to when I was 20, I'd probably slap myself in the face a couple of times," he said.
Watching Gonzalez emerge as a quality pitcher in Oakland and become a star with one of their division rivals, it is the Phillies who probably want to slap themselves in the face, especially when they recall the pitcher they acquired when they traded the young, emotional lefthander back to the White Sox.
Gillick dealt Gavin Floyd and Gonzalez in December 2006 for Freddy Garcia. It didn't take long for the Phillies to regret the deal.
"It really killed us to give [Gonzalez] up," Arbuckle said. "We were really reluctant to include him in the deal, but at that point we thought Garcia was a guy who could get us over the hump and help us win at the big-league level. Kenny Williams [the White Sox general manager] insisted he had to have Gonzalez back to make the deal. We tried shopping other names, but Kenny wouldn't bite."
Garcia arrived in Clearwater with a dead arm.
"It was horrible," Arbuckle said. "He came to spring training and he had nothing coming out of his hand. It looked like batting practice. We thought maybe he was a veteran getting ready for the season, but once the games started, he still didn't have anything."
Garcia won one time in 11 starts for the Phillies before being shut down with a shoulder injury.
Gonzalez, meanwhile, was traded from the White Sox to Oakland in a deal that included Nick Swisher, then landed in Washington last offseason and received a five-year, $42 million deal from the Nationals.
"I'm glad for him," Phillies general manager Ruben Amaro Jr. said. "It's not hard to watch him. We were trying to make a run [with Garcia] and it didn't work out. That's part of the game. He has bounced around all over the place since then. We tried to make a run at him when he was in Oakland and I guess [the Nationals] gave them a better package."
Contact Bob Brookover at email@example.com. Follow on Twitter @brookob.