Blues fans welcomed Drenthe with a huge roar for his debut against Aston Villa.
"I am having to look to build a new side from basically what we have already at the club because I can't bring in a whole load of new players," Moyes said.
"But it means the players here have got a chance, and I think we have some who can take it. You look at our bench, and the players who can come on all produced something.
"Drenthe has certainly got something, and you look at the performance of the Greek lad (Vellios) when he came on, and you say 'you're not the worst, are you son?'
"I have others like that too, so the challenge is to find a winning team, which will allow us to give some of those players a chance in the side."