For a round robin match, he played pretty well. His serve was off, but it didn't matter.
He stepped on the gas when he needed to in set #1, and was just steady enough in set two, to hold off Ferrer, who was playing reasonably well.
I don't think he wanted to lay it all down in the round robin stages. That being said, Djokovic and Murray will be tough, and Fed will have to serve well, and not lose focus at all.