But Keane said: "I have not even thought about his past. I have seen players move to clubs involved in derbies and Real Madrid players, for example, who have gone to Barcelona. I know he is from the area and it might drive him on a bit more.
"It is brave, without a doubt. I admire players who go against the grain. It is his career and, once we had spoken to Cardiff, he couldn't get up here quick enough.
"It was a positive step in his career and we are delighted to have him. If he plays it wouldn't surprise me if he scores, that's the way things go in football.
"I still believe, come the end of the season, he has a great chance of being our top scorer, although you might say that is not going to be difficult and he won't have to score many."