"It was nothing like this," he said, shaking his head inside the U.S. dugout before the XM All-Star Futures Game on Sunday.
"In high school, we got to play in Dodger Stadium, but never got to take batting practice and do all this."
Arenado is one of two Rockies prospects, along with World catcher Wilin Rosario, that competed on the same Chase Field turf that will be used in the 82nd Major League Baseball All-Star Game on Tuesday.
Arenado is hitting .308 with 11 home runs and 67 RBIs in 82 games at high Class A Modesto and hit .308 in 373 at-bats last year at Class A Asheville.
"Everything's going well right now," the 20-year-old third baseman said. "I'm just going to keep doing what I'm doing."
Almost a month earlier to the date, on June 11, Arenado hit a home run off Giants and former Cy Young Award winning pitcher Barry Zito, when the left-hander was on a rehab stint in Modesto.
"The count was in my favor, it was a good pitch to hit and I put a good swing on it," he said. "And it just went out."
It just went out to the deepest point of John Thurman Field.
"I did hit it pretty hard," he said.
Opposing Arenado for the day was Double-A Tulsa catcher Rosario, who is hitting .249 on the season with 12 home runs and 29 RBIs.
Rosario is in his sixth professional season, having debuted in the Rookie Leagues as a 17-year-old in 2006. Now 22, he is enjoying what looks to be, halfway through this year, his most power productive season.
"I feel great," he said. "It's been a good season."
Arenado said he's having a great time in Phoenix and that the best part has been meeting other players from both sides.
"There's a lot of different players here and a lot of great ones," he said. "I'm having a great time with all of them here.
"It's kind of like living the dream."
Anthony Fenech is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.