Heston is another good bet to have an impact on the Giants this year. He's the only minor league starter on the 40-man roster with experience at Double-A, making him the most likely candidate to enter the Giants rotation if someone gets injured or has performance issues.
He doesn't have an overpowering fastball, so he isn't ranked very highly by most prospect publications. However, all he's done in his minor league career is get guys out. In three minor league seasons, he's put up a 3.13 ERA overall. Last year at Double-A, he had a 2.24 ERA while whiffing 135 hitters in 148.2 innings.
He's a ground-ball pitcher with excellent control, which has helped him flourish in the minor leagues without jaw-dropping stuff. He walked only 40 hitters last season and gave up only two home runs to due his worm-killing sinker.
John Sickels, a prospect analyst for SB Nation, wrote that Heston is a better prospect than his radar gun readings indicate.
Heston does not have the same kind of stuff as the relievers behind him on the list, but he's much closer to the majors and has a chance to start so I want to highlight that. Throw the radar gun away with this guy. As Michael Fiers and Tom Milone show, you don't have to have a blazing fastball to get people out if you know what you're doing. Heston knows what he is doing.
Heston's understanding of how to pitch, proximity to the big leagues, ability to throw strikes and propensity to keep the ball on the ground could get him a spot in the Giants rotation as soon as this season. If not, with Barry Zito and Tim Lincecum set to become free agents at the end of 2013, Heston could have the inside track on a rotation slot for 2014.
Spring training doesn't mean a whole lot for the guys who already have jobs. However, for Brown, Panik, Hembree, Heston and the other prospects in camp, it's an opportunity to impress the Giants and make another jump towards the ultimate goal of playing professional games at AT&T Park.