The manager needs to get them to work. That is what he gets paid for.
The striker he had at Sporting was a reject from Coventry City.
They don't seem to be natural strikers, and they play that way. I'm sure he's doing what he can, as you say, he made Gyokeres into the most coveted striker in world football.
A reject? He was good at Coventry, that's why Sporting signed him.