He said: "Players in England are usually bigger, stronger and faster than those in Scotland. I mean no disrespect to Scottish players as I know there are some fine footballers in the SPL.
"But the Premiership is a league in which you have to take in players who are equipped in all ways in order to compete.
"Talent is merely one facet of a player's make-up required to make the grade in England.
"Height, pace and power are all needed in equal measure.
"So few Scots possess all the required qualities to survive down here.
"In the Premiership today you need to replace outgoing players with new ones who are both experienced and good enough to do the necessary job for the team straight away.
"You have to scour the world sometimes to find them and sign them, like we did at Wigan."