He said: "I'm over the moon that we are able to bring in two players of such talent.
"We've spoken about the profile we want here next year and what we are trying to do. The signings of Cox and Mills capture exactly what we are after.
"I can instantly see them in this team and see what they bring and they have a desire to be successful."
Back-row Cox came through the Warriors Academy and spent three years with the first-team before his switch to Gloucester in 2010.
And Ryan believes the flanker is eager to return and help drive his hometown club forward.
He admitted: "Cox is really passionate about trying to get the club into the position he would like to see it.
"Both him and Mills want to be first-choice and they want to push their claims."
The former England number-eight continued: "We've targeted people that are specifically the right fit and part of our situation is attractive to some of the real competitors out there.
"Bringing in a young English profile starts the wheels of this club moving again but we also need some people with more miles on the clock and with more experience in the Premiership.
"Those are two ends of the spectrum we're trying to get and we are starting to make some headway in identifying those people."
Ryan gave debuts to three youngsters last weekend in the trip to Sale Sharks and he insists it is another stepping stone in building the club.
He concluded: "You have to give the youngsters a chance and all credit to them.
"It highlights that some of them are inexperienced and that we have some ground to make up on other clubs.
"But by giving them game-time we get to see them grow and now we have started the conveyor belt of young talent coming through."