Martinez says that Jagielka has come back with experience that gives him a “head start” on players who haven’t played in a major tournament, and that will help him through the season.
“His experiences will make him more determined. He will be able to reach another level,” the Spaniard said.
“When you come back from that tournament, you are a better player. You just don’t get too high it is positive or too low if it’s negative.
“The mind-set changes and the experience of playing in a World Cup then gives you a head start on players who have never been in a World Cup.”