"It's gone extremely well," Harris said. "We're pleased with his progression, where he is physically and how he's performing."
Giolito strained his UCL as a high school senior last spring and missed the season. The Nationals selected him 16th overall, despite the possibility he would need surgery. He made one professional start last August before experiencing elbow soreness and undergoing Tommy John surgery.
Harris said Giolito made the most of the time while he was out.
"When you go through an extended rehab, you have a lot of time on your hands," Harris said. "He's done a great job developing his body. He's in excellent shape and is physically strong. He handled it with a great deal of maturity."
Now that Giolito is healthy, he is once again dominating hitters. He struggled in his first outing, retiring only one of the four batters he faced, but fared much better in his next two starts, throwing five innings combined, striking out six and allowing four hits.
Giolito's fastball was clocked as fast as 100 mph in high school. He also throws a power curveball and a changeup. Harris, who was at Giolito's most recent start on Monday, said his stuff is returning.
"I was really, really pleased with it," Harris said. "The fastball velocity was good, it had good life and carry and he threw it for strikes. His curveball had above-average depth and finish and he's continuing to develop his changeup."
Giolito is building to a point where he can throw five innings per start, Harris said. The Nationals' plan is to continue starting Giolito every fifth or sixth day for the rest of the season. As for where those starts take place, Harris left open the possibility of a promotion, saying they will "take that as it comes."
For now, however, the Nationals are just happy to have Giolito healthy and back on the mound.
"I can't emphasize enough with how pleased we are about he went through process and where he is on the back end," Harris said.