On May 8, 2013, Dietrich saw his first big league action, and his first at-bat was a single off San Diego's Jason Marquis at Petco Park.
Fast-forward to now, and Dietrich once again was starting at second base on May 8 against the Padres at Petco.
"It's pretty cool," the 24-year-old said. "I was excited anticipating coming back here, knowing this is where it all started for me. It's where I made my debut and had that first hit. It's always going to be special, always a park and a place I remember and look forward to."
Last year, Dietrich's parents made the trip to San Diego and went along when the Marlins played the Dodgers in Los Angeles.
On Thursday, his family was back home in Cleveland, Ohio. Dietrich's parents also are in possession their son's first hit ball.
"The park is beautiful and the place is great," Dietrich said. "It's a special moment for me."
A left-handed hitter, Dietrich has mostly platooned at second base. But as he continues his development, the Marlins see him as an everyday big leaguer.
"You talk about young guys developing, he's come a long ways," manager Mike Redmond said. "That's a testament to him. Last year, he got his feet wet in the big leagues. That was huge for him.
"This guy, he can hit. You watch him, the way he runs balls out. He wants to get the big hit. This guy is a gamer. He wants to contribute."
Joe Frisaro is a reporter for MLB.com. He writes a blog, called The Fish Pond. Follow him on Twitter