WEST PALM BEACH, Fla. — When the Mets’ Jacob deGrom struck out Houston Astros outfielder Josh Reddick in the first inning Saturday, he turned and faced the scoreboard at the Ballpark of the Palm Beaches. He liked what he saw: 97, as in miles per hour on his fastball. DeGrom’s old friend was back.

DeGrom, 28, had surgery on Sept. 21 to reposition the ulnar nerve in his right elbow, on his pitching arm. The operation ended a frustrating season in which he had a solid E.R.A. (3.04) but a diminished fastball. He hoped to feel sharp in his spring training debut on Saturday, and he did, retiring all six batters he faced, with three strikeouts and a crisp fastball that consistently hit 96 m.p.h.

“First outing off surgery, things went the right way,” deGrom said. “I was a little nervous. I get nervous before every start in the season, but not really that much in spring.”

Facing the Astros’ everyday lineup, deGrom threw only fastballs in the first inning, getting a groundout, a strikeout and a pop-up. In the second, he sandwiched a flyout between two strikeouts. DeGrom said he had hit his spots with nearly every pitch and had fixed a mechanical flaw that was causing him to leave his pitches flat in the strike zone.