The wide receiver has recorded 106 receiving yards and scored a touchdown during the NFC East side's last three pre-season games.
The quarterback told the team's website: "Honestly, Miles has gotten to a point where he's invaluable for us, just because he can play multiple positions, and his strength inside really gives him an advantage.
"But his knowledge of the game and his explosiveness allow us to do a lot of different things offensively. He continues to grow and each week he gets better and better.
"We just have to keep doing the things that come up over and over at his position and what specifically he's going to see a bunch. Just the little things, but he's doing a good job, and he's grasping it, and each time I communicate with him he seems to get after that, so that's a real good thing."
The Cowboys play the Houston Texans in their final pre-season game tomorrow night.