Five days later, the Giants prospect did just that, fanning 11 and allowing one run over six innings Sunday afternoon as the Double-A Richmond Flying Squirrels defeated the Trenton Thunder, 5-2.
"It's awesome," he said. "I'm finally over the hump."
A winner of four straight decisions, Heston (5-2) gave up six hits -- including Jose Gil's two-out RBI single in the second -- and four walks. Perhaps more impressive than his string of strikeouts, he had not allowed an earned run in 33 innings, a stretch that dated back to April 30.
"I was aware of it, but it's also something I didn't try to think about it," said Heston, who threw 64 of 98 pitches for strikes. "Luckily, they got it out of the away early, so it was off my mind."
Nine of the 24-year-old right-hander's final 11 outs came on strikes.
"I actually struggled a little bit," he said. "The command of the fastball wasn't there as it has been, so I had to resort to breaking balls -- my breaking ball and slider. I was able to throw it for a strike when I needed to and was able to bury it when I needed to. I think every single one of [the strikeouts] came on breaking balls."
After another strong performance, his 0.70 ERA and 59 strikeouts over 64 2/3 innings both lead the Eastern League.
The 2009 12th-round Draft pick won 12 of his 16 decisions last year at Class A Advanced San Jose, where he compiled a 3.16 ERA in 24 starts. Over 151 innings, he fanned 131.
Heston credited his success this season to his work last year with San Jose pitching coach Brian Cooper, plus his newfound ability to execute pitches even when he falls behind in the count, as was the case Sunday.
The Flying Squirrels scored their first four runs off starter Vidal Nuno. Chris Dominguez and Juan Perez contributed RBI singles in the fourth and Tommy Joseph singled home another run in the fifth.
Five in the lineup, including Dominguez, Joseph and leadoff man Gary Brown, all among the Giants' top prospects, recorded two-hit games. Brown raised his average to 255.
"He's started to figure it out," said Heston, who played alongside Brown in San Jose in 2011. "Once he figures it out, there's no stopping him."
Nuno (0-1), making his second Double-A start, was charged with four unearned runs on nine hits over five frames.