The young Mexican was signed by the British team to replace Lewis Hamilton this year and beyond, but some linked the deal with his commercial ties to billionaire Carlos Slim.
He struggled notably in China, admitting it "wasn't my best weekend in terms of pace".
Perez also got caught up in on-track incidents, most notably with Kimi Raikkonen, who screamed 'What the hell he's doing?' after being run wide and colliding.
When the Finn discussed the incident in the green room prior to mounting the podium, third-placed Hamilton agreed: "He (Perez) was all over the place."
Martin Brundle, a former McLaren driver turned British commentator, is quoted by Speed Week as suggesting Nico Hulkenberg would have been a better pick for 2013.
"I still don't understand why McLaren didn't sign this guy (Hulkenberg) up," he said. "His talent is abundantly clear.
"I would have signed him ten times before (signing) Perez," added Brundle.
For now, McLaren boss Martin Whitmarsh is backing his new 23-year-old driver.
"In terms of the (Raikkonen) incident, I said to him (Perez), 'You have to be out there racing'.
"That means sometimes you've got elbows and you've got to be robust without being dirty."