Moyes has praised the summer signing ahead of tonight's Europa League group opener again FK TSC Bačka Topola.
He said, "He added things to Southampton which were terrific, whether that was scoring goals or making goals. I hoped that if we could transfer that from there to us, then it would give us some options as well.
"He can play several different roles in midfield for us and I think he's been a good, steady signing for us so far. Getting his goals and assists [has been great], and we've always thought we've been a side who have not been bad at set pieces, so if we could get a really top, top deliverer then it would make us even more potent.
"He's added a couple of open play goals at the moment too, so I have to say it's been a great start to his West Ham career and I hope we can continue the levels that he's at."