Spanish football expert Guillem Balague has insisted that Isco is too poor a player to thrive at Real Madrid.
The 23-year-old began his career at Valencia, then had a stint at Malaga before moving to Madrid in 2013 for a reported fee of €30m (£23m).
Despite a decent return of eight goals from 32 league appearances in his debut season, Isco has since struggled for form and has found the net just twice in 24 attempts so far this term.
"Quite simply, he is not good enough for Real Madrid," Balague wrote in his column for Sky Sports. "He is not consistent so he gets frustrated by being in and out of the team, and that turn affects his consistency.
"It's a vicious circle if you would like to use that analogy. He hasn't reached the level he should be at. He was perfect for clubs of Malaga, Sevilla or Villarreal's stature, but not good enough for Real."
Asked about the possibility of Isco joining Arsenal this summer, Balague was adamant that the Gunners have no "need" for his services.
"Many people will say Isco is a typical Arsenal player," he added. "He is an elegant player who fails to fulfil his potential, doesn't score or assist enough and doesn't work hard enough without the ball.
"For me, he is not a player Arsenal need. That doesn't mean he won't go to the Emirates, the transfer market can serve up anything, I just feel he is a not a player for Arsenal."
Isco has also been a reported transfer target for Manchester City and Manchester United.
