The right-hander threw 65 of his 93 pitches for strikes and gave up one run on three hits and no walks.
"He's getting a lot more consistent with having an overpowering fastball," Salem pitching coach Paul Abbott told MiLB.com. "His command, his location is getting a lot better, his confidence is growing and he's just evolving as a pitcher as he's logging innings."
MLB Pipeline's No. 77 overall prospect has posted a 1.29 ERA through 10 starts across two levels after his season got off to a late start.
Kopech has also been piling up the strikeouts. The Red Sox prospect struck out seven in a row from the second to the fourth Thursday night and has fanned a total of 75 through 48 2/3 innings this year.
The rest of the best performances from top prospects Thursday:
• Brendan Rodgers (Rockies' No. 1) did a little bit of everything for Class A Asheville. The No. 7 overall prospect hit a pair of homers and scored four runs as part of a 3-for-3, four-RBI night. The power display was Rodgers' second two-homer game of the season. The 2015 first-round selection has two or more hits in three consecutive games.
• A pair of Indians' prospects had good showing in Class A Advanced Lynchburg's doubleheader. Bobby Bradley (Indians' No. 3, No. 76 overall) went 2-for-6 with a homer and two RBIs in the two games, while Tyler Kreiger (Indians' No. 16) went 4-for-7 with two RBIs. Bradley has hit four homers in his past seven games and has a career-high 93 RBIs.
• Taylor Ward (Angels' No. 3) hit his fifth and sixth homers of the season in his first career multi-homer game. The Angels' 2015 first-round pick went 2-for-3 and drove in four runs for Class A Advanced Inland Empire.
• Cubs' No. 3 prospect Jeimer Candelario has reached base in 25 consecutive games for Triple-A Iowa. The 22-year-old hit a home run, his second in as many games, and went 2-for-4.
• Marlins' No. 4 prospect Brian Anderson put together his second four-hit game of the season for Double-A Jacksonville. Anderson went 4-for-5 with a pair of RBIs and has hits in seven of his past eight games.
• Home runs are starting to come in bunches for Nationals' No. 5 prospect Carter Kieboom. Washington's first-round selection went 1-for-3 with a homer and three RBIs for the Rookie-level GCL Nationals. Kieboom has hit all four of his professional in the past six games.
• Orioles' No. 12 prospect D.J. Stewart had a perfect day at the plate for Class A Advanced Frederick. Stewart hit his seventh home run -- his first since July 11 -- and put together his seventh three-hit game of the season with a 3-for-3 day.
• Phillies' No. 18 prospect Nick Pivetta struck out a season-high nine in just his second start with Triple-A Lehigh Valley. The 23-year-old was recently promoted and has impressed so far. Pivetta fired 64 of his 101 pitches for strikes and scattered three hits across six scoreless innings.
• Jose Trevino (Rangers' No. 22) continued his hot August with hits in both halves of a doubleheader for Class A Advanced High Desert. Trevino combined to go 4-for-6 with a double, a homer and four RBIs in the two games and now has hits in 11 of 15 contests this month.
• After some rough starts to begin the month, Royals' No. 25 prospect Corey Ray appears to be back on track. The 23-year-old was charged with just one unearned run in seven innings with Class A Advanced Wilmington and has now given up just the one earned run over his past 12 frames.
• Aristides Aquino (Reds' No. 20) is making a habit of jogging around the bases. The 22-year-old went deep in both halves of Class A Advanced Daytona's doubleheader, bringing his season total to 23. Aquino has homered in three consecutive games and hit seven long balls in his past eight contests.
• Red Sox No. 13 prospect Roniel Raudes has given up one earned run or fewer in four consecutive starts after spinning seven scoreless frames for Class A Greenville. The 18-year-old struck out four and gave up four hits in his longest outing of the year.
• Bobby Dalbec (Red Sox No. 21) hit a pair of homers for Class A Short Season Lowell. The 2-for-4, three-RBI game was the first multi-homer performance of Dalbec's professional career.
"The first one was a little higher," Dalbec told MiLB.com. "The second one was mid-thigh, first one around the belt. I overswung on a fastball inside, worked the count to 3-2 and just told myself to be easy, use my hands and really focus on seeing the ball as deep as I can. [Gutierrez] had a fastball a bit more flat [than Chavez's], so I had to adjust my approach -- swinging for the middle of the ball instead of the bottom of the ball. He left one middle-out, and I put it out over the right-field fence."
• Fernando Romero (Twins' No. 7) fired another gem for Class A Advanced Fort Myers. Romero fanned eight and gave up just three hits in 6 1/3 scoreless innings. The right-hander hasn't allowed an earned run in either of his past two starts and has struck out 19 in that span.
• White Sox No. 25 prospect Luis Martinez continues to put zeros on the board for Class A Kannapolis. Martinez set a career high with nine strikeouts in five scoreless innings and has now given up just one earned run over his past three starts (17 total innings).