The 23-year-old completed a move to the Santiago Bernabeu after starring for his country at the World Cup this summer, in a deal which effectively ended Angel Di Maria's time at Madrid as he was sold to Manchester United.
However, James has since scored just three goals in 12 appearances for Carlo Ancelotti's side, with critics quick to compare his output to that of Di Maria, but Valderrama believes he will soon justify his hefty price-tag.
"James showed his quality in the 2014 World Cup in Brazil," he is quoted as saying by AS.
"The mere fact that he has adapted to an important group of quality players who are already established, has merit on its own. And for one so young like he is, even more so.
"It's an important period for him to learn. [The transfer fee] is a normal figure. Madrid paid what James is worth.
"Now it's his chance. He's 23 and hopes to last at Madrid for a long time."