The Irish striker became the second Killie player to score a hat-trick at Tynecastle as the visitors claimed a third win from three games in the Scottish Premier League against Hearts this season.
Shiels said: "He's gotten the chances and he's put them away and you have to give him credit because you look at what he is playing against. There are three international defenders in there.
"It was a good outcome and the boys have showed good character again. To beat a club the magnitude of Hearts three times in one season is a terrific record for the boys.
"What you get in February every year is pitches that are not as fluent. That means there is a reduction in the passing volume you can achieve in the game.
"I was pleased with the way we passed it. I think we counter-attacked well. The dove tail in our co-ordination of the movement was outstanding."