Keane said: "I saw myself last season how difficult it can be to settle into a new club and it's even harder for him because he's had to come to a new country.
"So to settle in the way he has, and produce the quality he has consistently throughout the season, is outstanding.
"We see the quality he has every day in training, he's shown that consistently across the season and I still think there's more to come from him as well.
"I think he's the perfect mix for a modern-day full back. A lot of the time these days you either get a (full back) who is a really good defender or someone who is more of a winger."