The 22-year-old was one of the hottest properties in the transfer market this time last year but his stock has fallen slightly after a difficult season for Everton. Stones is a talented reader of the game and distributor from the back, but costly errors have left a question mark over his readiness to play at the highest level. Chris Smalling is expected to take one of the spots in central defence but Roy Hodgson must decide whether to partner the Manchester United man with either Stones or the more experienced Gary Cahill. Campbell, who played 71 times for England and was named in the FIFA team of the tournament after the 2002 World Cup, has no doubts whom he would pick. "If you keep making mistakes at international level, you're going to suffer because one mistake in a tournament and you can be out," Campbell said. "If you make mistakes at a domestic level, you have more time to learn. He is learning.