At least it was significant enough for general manager Brian Sabean to show up with some of his top assistants in tow and watch most of the six innings that the squads played.
As starting pitchers, Heston and Kickham would be valuable commodities under any circumstance. This year, with the rotation's long-term composition in doubt, the 24-year-olds are drawing considerable attention from the club's decision makers. Tim Lincecum will become eligible for free agency after this season, and whether the Giants will pick up Barry Zito's $18 million contract option for 2014 is questionable.
Moreover, preparing for untimely factors such as injuries or ineffectiveness is a must for the Giants, whose rotation has remained among baseball's elite since 2009. One way or another, the Giants might need Heston and Kickham, -- who thrived at Double-A Richmond last year -- sooner rather than later.
"Well, that's the plan," manager Bruce Bochy said when asked if the pair can potentially contribute on the Major League level this year. "We need depth in the organization. Those are two guys we think a lot of. Hopefully, they continue their progress and if we need them at some point this year, they'll be ready."
Heston looked ready against the aspiring D-backs, allowing two hits and striking out four in three shutout innings. D-backs ace Ian Kennedy dominated the Giants' farmhands and yielded one hit in four innings, including three innings in which he retired four hitters. Yet Heston, rated eighth by MLB.com among Giants prospects, didn't look overmatched.
"He's a right-hander who likes to spot up, so he's a good guy for me to watch," Heston said of Kennedy.
Sporting a fastball that ranged between 87-91 mph, Heston wasn't overpowering. But he repeatedly coaxed harmless ground balls by keeping his offspeed pitches low and using his sinking fastball.
"It was good to get the ball down in the zone and let the defense work," said Heston, who led the Eastern League with a 2.24 ERA last year.
Heston credited Steve Kline, the former Giants reliever who was his pitching coach with Class A Augusta in 2010, for teaching him the sinker that has become such an essential pitch for him.
"It gave me a lot more confidence to throw the ball over the plate instead of trying to be so fine," Heston said. "... I could rely on the sink to still get a ground ball. That really helped."
Kickham, rated 12th among MLB.com's Giants prospects, allowed one run and two hits in two innings. But his fastball, which hovered between 91-93 mph, looked lively, as did his other pitches. Relieving Heston, he struck out the side in the fourth inning.
Kickham has improved rapidly since a cracked fingernail in Spring Training of 2011 prevented him from beginning the season until mid-May. He finished 5-10 with a 4.11 ERA that year with Augusta before posting an 11-10 record with a 3.05 ERA last season for the Flying Squirrels. He and Heston were named to the league's postseason All-Star team as its left- and right-handed starters, respectively. It marked the first time since the league adopted this method for selecting All-Stars that pitchers from the same team claimed both awards.
Not that long ago, right-hander Matt Cain was in the developmental stage that Heston and Kickham now occupy, possessing legitimate ability but unsure of how to harness it. So Cain was pleased when the pair approached him recently to quiz him about various aspects of pitching. It reminded Cain, a three-time National League All-Star and San Francisco's Opening Day starter, of when he sought advice from veterans such as Matt Morris and Jason Schmidt.
"They're eager to learn," Cain said. "Both of those guys were asking questions the other day. I loved that. That was great."
It might not be long before Heston and Kickham are asking for directions to AT&T Park.