Stones has faced criticism for the first time in his career of late, with many of his performances being labelled as erratic.
The youngster has been built up as England’s best defensive prospect, but Merson believes that Stones needs to change his style if he is to fulfil his obvious potential.
“Of course [he needs to change],” Merson stated. “I want to see a centre half who can defend first of all and then we’ll play from there.
“I mean, he gets all the accolades because he’s the only one who can pass out [in England]. But Tony Adams and Paul McGrath would be in everyone’s top 10 defenders, and what did they do? Head it out and kicked it out.
"It’s terrible, it’s shocking. If the manager doesn’t pull you after that [Stones’ dribble inside his own area against Tottenham] and say what are you doing, then he never will.
“I don’t think he’s learning. Forget about the passing, his positional play is bordering on atrocious.
“It’s alright saying he’s a kid, but Dele Alli is 19. He’s 21. He's got to be better. It frustrates me.”
Stones was brilliant for Everton in his first full season of top-flight football, and his performances attracted the attentions of Chelsea over the summer.
It was expected that the 21-year-old would kick-on over this campaign, but his performance levels do appear to have dropped.
Stones has played a key role in an Everton back-four, which has leaked goals throughout the campaign so far.
The Toffees have let in 34 goals in their first 23 matches, and Roberto Martinez’s side’s defensive vulnerabilities has led to them failing to live up to expectations this term.