Saha scored two in the 3-0 victory at Goodison Park on Sunday.
Moyes said: “We signed Louis when we were very short of forwards through injury, and he had been having his own injury problems. Many people said it was a bit of a gamble.
“But his ability is outstanding. I have not worked with that many players with that sort of quality.
“Louis is right up there with the best I have ever managed. A lot of people beforehand had signed him for his talent and goals.
“But he now looks like he is enjoying himself, and the goals he is getting are the bonus.
“Louis wants to prove that he is not injury-prone, like lots of people said he was, when he came here.
“He had a year or two when he had bad injuries, but he wants to show everyone that he is not injury-prone, and he is getting a run of games and goals now to make his point.”