In Sunday's 4-2 loss to the Padres at Marlins Park, Dietrich committed an error on San Diego's Tommy Medica's routine grounder. It didn't lead to a run, but Nathan Eovaldi had to face two more hitters in the second inning.
Dietrich has committed two errors in 25 innings this year. As a rookie in 2013, he made two errors in 502 1/3 innings.
"I've got to just get back to the basics," he said. "I kind of feel like I was rushing a little bit lately. I just have to be a little more aggressive to the ball, but under control, and just kind of smooth it out a little bit. It is kind of unlike me. My defense has been pretty steady throughout my time in the big leagues and the Minor Leagues."
Initially, Dietrich was charged with three errors, but one was overturned by an MLB review. On a grounder by Tommy Medica, Dietrich's throw was was ruled his error. But the overturn gave the error to first baseman Garrett Jones.
Dietrich noted Tuesday that he was unaware the review was initiated by his agent, David Meter.
"I found out that was on my agent's part, without me having any knowledge," Dietrich said. "It's not what I'm about. I wasn't actually happy about it going to a teammate. I made sure I made it clear that won't ever happen again."
Dietrich has been platooning at second base with Jeff Baker. With the Nationals starting lefty Gio Gonzalez on Tuesday, Dietrich wasn't in the starting lineup.
Pregame, Dietrich continues to work with infield coach Perry Hill on the basics.
"It gets back to being aggressive to the baseball, but under control, so I don't have to rush," he said.
Joe Frisaro is a reporter for MLB.com. He writes a blog, called The Fish Pond. Follow him on Twitter