The 24-year-old beat Matt Flynn to the starter's role during the AFC West side's training camp in pre-season and has led the team to three wins in their first seven games.
The Raiders' head coach told reporters: "I've seen a lot of development from him. I think he's improved himself as a quarterback. I think he's improved himself as a passer in the pocket.
"He's still got a lot of things that he needs to improve on. I think he's done an outstanding job and I think he's going to continue to get better as we move forward, and the more experience that he gets and the more things that he has the opportunity to see, the better he's going to be when he gets in those types of situations again.
"I think the big thing that I want to see with Terrelle is that I want to continue to see the consistency, and that's what you deal with a lot of times with young players is that they're a little bit inconsistent. He's got to continue to get to work."
The Raiders face the Philadelphia Eagles later today.