Matz, who was 9-8 with a 3.40 ERA in 22 starts last season, is on the disabled list with a sprained flexor tendon.
Before Sunday's game against the Pirates, manager Terry Collins said he had not yet talked with anyone about Matz's outing but was impressed with his pitching line, especially given the hitting-friendly tendencies of the Vegas ballpark. "Five perfect innings in Las Vegas? I've played a lot of games in Las Vegas and I'm not sure I've ever seen that," Collins said.
With the heat, thin desert air and hard infield, the park is not conducive to that kind of pitching.
"The ball flies out of the park," Collins said. "It's a tough place to pitch."
On the downside, Collins said he had no update on Cespedes, whose second rehab start was put off indefinitely after he experienced soreness in his right quad while running the bases in his first rehab game Friday. The 2016 All-Star went on the 10-day disabled list April 28 with a strained left hamstring.
Lugo works 6 innings
Later on Sunday, right-hander Seth Lugo pitched six innings in a third rehab start with Double-A Binghamton, allowing three earned runs on eight hits with seven strikeouts and two walks. He threw 79 pitches, 55 for strikes.
Lugo has not pitched this season after going on the DL in March with a partial tear of the ulnar collateral ligament in his right elbow. He was 5-2 with a 2.67 ERA in 17 games, including eight starts, last season.
Bob Cohn is a contributor to MLB.com based in Pittsburgh. This story was not subject to the approval of Major League Baseball or its clubs.