Reds boss Kenny Dalglish signed the 21-year-old after he impressed during Uruguay's Copa America triumph in the summer.
Scales has backed Coates to make his own mark on the Barclays Premier League with Liverpool under the guidance of veteran defender and club legend Jamie Carragher.
"I've seen glimpses of him in action for Liverpool and during the Copa America. He's obviously adapting to the pace of the Barclays Premier League and that will take him a little bit of time, but I like what I've seen," Scales told Liverpoolfc.tv.
"He won the young player of the tournament at the Copa America so you can see that he is a talent. I think having [Luis] Suarez there, a fellow Uruguayan, will help him too.
"I think he's got a good mental attitude and the right personality to be a success at Liverpool.
"He can only benefit from having the likes of Jamie Carragher there; senior players who can help him to progress and improve as a player.
"They know all about the ethos of the club and I think he'll be excited about learning more and bedding in at Liverpool. I expect him to be central part of that team over the next few years."
Meanwhile, Liverpool legend Tommy Smith believes Carragher has all the qualities necessary to manager the Reds in the future.
Carragher only recently admitted his career may soon be coming to a close, and has made no secret of his desire to enter coaching when he eventually retires.