Harris fanned a career-high 11, nearly tripling his previous high of four.
"I was able to throw all four of my pitches for strikes today," Harris told MiLB.com. "And I got some big swings and misses at key times."
Harris was stuck with a no-decision, but is 2-0 with a 1.05 ERA this season.
The rest of the best performances from top prospects Wednesday:
• If there's a teammate on base, odds are Alex Bregman will drive him in. Bregman, the No. 19 overall prospect, has seven RBIs over his last three games, including two for Corpus Christi on Wednesday. The Astros' top prospect went 2-for-4 with a homer.
• Anthony Alford may have found his swing. The Blue Jays' top prospect was mired in a deep slump, that dropped his average to .106, but the outfielder has hits in each of his last three game and recorded his first multi-hit game of the season on Wednesday. After going 2-for-4 with a double and three RBIs for Dunedin, Alford is hitting .153.
• Cubs' No. 18 prospect Mark Zagunis was 4-for-4 with a double for the Tennessee Smokies. Zagunis, drafted in the third round of 2014, now has four career four-hit games.
• Adalberto Mejia gave up more runs Wednesday than he had in his previous two starts combined. The Giants' No. 10 prospect gave up two runs in 7 1/3 innings for Richmond and has given up three earned runs in three starts this month.
• Chase De Jong threw seven scoreless innings in the first game of Tulsa's doubleheader. The Dodgers' No. 18 prospect struck out six and allowed just four baserunners, two walks and two hits. De Jong may have done the heavy lifting, but he had the help of Alex Verdugo and Cody Bellinger. The No. 6 and No. 5 prospects in the Dodgers' system hit back-to-back homers in the seventh inning.
• If teams are expecting to score a lot off Phillies' No. 13 prospect Zach Eflin, they better think again. The right-hander has held opponents to one earned run or less in five of seven starts this season and did so once again Wednesday for Lehigh Valley. Eflin carved his way through seven scoreless innings, surrendering just two hits and a walk.
"Today was all about staying with the game plan and attacking with the fastball as much as I could," Eflin told MiLB.com. "I think we did a good job of getting quality strikes. [Catcher] Andrew Knapp and I were on the same page in that regard. I don't think I shook him off once. We were just being aggressive, challenging hitters and it worked really well."
• Rays' No. 3 prospect Willy Adames hit two homers for his first career multi-homer game for Montgomery. Adames, the 77th-ranked prospect, had three RBIs.
• What better way to break out of a slump than with a grand slam? Well, that's exactly what Reds' No. 7 prospect Tyler Stephenson did. The Dayton catcher was hitting just .148 through his first 19 games, but broke out Wednesday, going 3-for-6 with a grand slam and a career-high five RBIs.
• When the Pensacola Blue Wahoos need innings, they can count on Amir Garrett. The Reds' No. 4 prospect turned in another quality start Wednesday, giving up one earned run over six innings. Garrett has thrown at least six innings in seven of his eight starts this season.
• JaCoby Jones is back and trying to make up for lost time. The Tigers' No. 8 prospect finished serving a 50 game suspension for a second positive test for a drug of abuse and is now 4-for-8 in two games for Erie. Jones went 2-for-4 on Wednesday with a double and his first RBI of the year. He drove in 80 runs a season ago.
• After striking out a season-high 10 in his last start, Yankees' No. 10 prospect Ian Clarkin fanned just three Wednesday, but the 21-year old Tampa starter was just as dominant. Clarkin, a left-hander, gave up one earned run in seven innings - the fifth time he's held an opponent to one earned run or less this season.