The 24-year-old completed 10 of his 11 passes and led his side on a 99-yard drive to score a touchdown ran in by Bryce Brown.
Foles and fellow quarterback Michael Vick are in a two-way fight to win the starting job at the Eagles this season.
Kelly told reporters: "That's what I expect out of Nick. I think he's an outstanding quarterback, and I said that when we made the decision with Mike.
"I feel like our two quarterbacks are NFL-quality quarterbacks. We expected him to do that. That's the type of player that he is."
Philadelphia open their regular season campaign against the Washington Redskins.