Los Angeles Dodgers right-hander Roki Sasaki looked like he had settled into his role as a Major League starter until Friday’s start against the Arizona Diamondbacks.

Sasaki’s night ended after four-plus innings where he gave up five earned runs, two walks, and threw zero strikeouts. The Dodgers rookie has a 4.72 ERA and 1.485 WHIP across eight starts this season.

The 23-year-old recorded zero whiffs on his fastball Friday, an indication that the pitch that was once so electric for Sasaki in Nippon Professional Baseball has not yet arrived to the big leagues. Sasaki faced 20 batters and didn’t generate a single swing-and-miss.

A concerning trend from Sasaki’s start at Chase Field was diminished velocity, but manager Dave Roberts said he isn’t worried about that. What Roberts is more concerned about is Sasaki’s poor command.

“Because if you don’t have velocity when you’re talking 98, 99 (mph), then command becomes more of a priority,” Roberts said. “When you’re throwing mid-90s, 94, then you have to really command the baseball. So that’s what we’re going to work on as a group. Roki understands that. And this is still his first season here, so there has to be some grace, as he’s kind of learning this league and kind of getting his footing.”

In terms of velocity, Sasaki admitted that he and the Dodgers are “really still in this process of finding out what the root cause (is).”