John Stones has lost his place in Everton's starting line-up recently.
Alan Shearer was one of a number of pundits who criticised Stones after midweek, following his performance for England.
Shearer stated in his column with Coral that Stones simply had to learn and start cutting errors out of his game if he was to fulfil his potential.
However, Martinez has responded to those comments by insisting that Stones is well ahead of where he should be for a 21-year-old player.
“I would go back to say that he’s 21 and he’s already been an important player in our first-team for three season,” Martinez said.
“I think it’s remarkable - the contribution he has had on our team. But if you think at 21 you are going to be the finished article then you are in the wrong game.
“It highlights the incredible potential that John has, when everyone goes into that level of scrutiny for someone so young that is well ahead of where he should be at that age.”
Stones was held accountable for the first goal that England conceded against Holland, after his slip proved costly.
The error rather compounded what has been a disappointing few months for the young defender.
Stones has struggled this season, and his confidence has visibly been affected by his failure to regain to his top form.
Stones has lost his place in Everton’s starting line-up of late, and he also faces a fight to make it into England’s squad for EURO 2016 now.