A third baseman by trade, Headley was asked to give the outfield a whirl one month before the start of Spring Training as the organization looked for ways to get its top position-player prospect into a lineup that already included a third baseman in Kevin Kouzmanoff.
Suddenly, the "hot corner" looked like a breeze compared to this.
"I was a little rough around the edges out there, that's for sure," Headley said. "Playing the outfield was tough for me. When it is not something you usually do ... it's difficult.
"Let's hope that chapter has passed and I'll be in the infield for the rest of my career."
Sitting in a clubhouse chair before a game last week, the 28-year-old looked and sounded like someone who has found not only a level of comfort and success but possibly a level of acceptance from fans that eluded him for much of his career until now.
Headley goes into Friday's series opener against the D-backs leading the Padres in just about every notable offensive category: hits (127), average among regulars (.274), home runs (21), RBIs (78) and walks (66). The 21 home runs are a career high, easily surpassing the 12 he hit in 2009.
"To Chase's credit, his mind-set has shifted to where he's now the aggressor," manager Bud Black said. "You can say that early in his career, the pitcher took it to him. Now he is taking it to the pitcher."
A switch-hitter, Headley has closed the once-mountainous gap in his left-right splits and, perhaps more important, has even managed to tame roomy Petco Park, which usually devours left-handed hitters with power, often turning them into aggravated banjo hitters.
"It's fun to watch," said hitting coach Phil Plantier. "It's fun to watch a guy figure it all out and see him piece it together. I don't see any reason why this isn't going to be normal production for him for the rest of his career. This is not a fluke. This is very real."
That statement might very well draw a collective "What took so long?" groan from impatient fans, many of whom have been waiting for this kind of production from Headley.
Since Black took over as manager in 2007, no player has elicited such polarizing opinions on his watch as Headley. Not Jake Peavy, not Adrian Gonzalez. Some have been enamored with Headley's durability and his ability to reach base. Some have complained about his lack of power and that he tries to walk too much.
"You can take his statistics and put them in front of 10 people and you'll have five people say he's having a really good year, and the other five will say that he's not," said Darren Smith, the host of a popular talk-radio show on the Padres' flagship station, XX 1090 AM.
"I think that this is the first time in his career that the fans have been united in their opinion about him."
A surge in power will tend to do that, though Headley certainly had his merits before this season. There's a lot to like, especially his durability, as no player in the National League has played more innings than he has. Headley has turned himself into an above-average defensive player, and he's been a terror at the plate on the road, where his last two seasons have produced a .305/.392/.493 line.
"I know when he comes to Arizona, he wears us out," said D-backs general manager Kevin Towers, who held the same post in San Diego in 2005, when the organization drafted Headley.
Towers thought that the Padres might have "reached" some in selecting Headley in the second round out of Tennessee, with the team falling hard for his acute pitch recognition and ability to square up a ball on the sweet spot of the bat more often than not.
What kind of player does Towers see now?
"It's the full package now," Towers said. "He's got a good head on his shoulders, the power is starting to come, which makes him a complete player. He's an above-average defender at third. He's gotten better and better each and every year, and has done so in that [big] ballpark."
It was toward the end of last season when Headley started thinking of ways to remake himself for 2012. He hit four home runs last season. Even though Headley missed six weeks after fracturing a finger in August, four home runs were unacceptable to him.
Headley hunkered down this past winter in the cage, devoting himself to creating more loft on the ball. Plantier flew to Tennessee to talk hitting and to look at his swing. The mechanical changes Headley made were actually minimal.
It was the approach that altered dramatically.
"I wanted to take a pitch I could handle and put backspin on it and hit it to right field," Headley said. "I think before, I concentrated so much on hitting the ball the other way and hitting ground balls, I almost lost the feel to take a pitch and drive it."
Headley's success this season -- and the fact that he's under team control for two more -- made him an attractive target of opposing teams leading up to the July 31 non-waiver Trade Deadline. He's not sure what his future holds in San Diego, as the team has given extensions of multiple years to five players since March.
"Right now, we've got Chase through 2014," said Padres GM Josh Byrnes.
Projections have Headley making around $6 million this season, and the team has prospect Jedd Gyorko, who is destroying pitching in the Pacific Coast League, waiting in the wings. San Diego could make a deal this winter, or it could simply go year to year with Headley.
"There's really not a whole lot of clarity there," said Headley. "I know I'm under team control for two more years. So if they don't trade me, I'm going to be here. I want to be here. I take pride that this is the only organization I've ever played for. But we'll have to wait and see."