Nelson Piquet jr, who was Alonso's teammate at Renault in 2008 and 2009, thinks the 2012 Ferrari has been outclassed by the likes of Lotus and Sauber this season.
"The Ferrari is worse than those two, but sometimes a miracle is done because of Alonso.
"I think if he was in a Sauber or Lotus he would be world champion easily," the Brazilian, who switched to Nascar after the 2009 'crashgate' scandal, told Jovem Pan radio.
"I see those cars (Lotus and Sauber) in the front sometimes, but there is always the question: is it the car or the driver?" added Piquet, now 27.
The Brazilian looks back at his F1 career with some sadness, but insisted: "Alonso was not guilty of anything. It was great to have a teammate of his level.
"Before, when I was testing with Fisichella and Kovalainen, I could go at the same pace, but when I started to be with Alonso, I was suddenly half a second slower.
"Alonso made me work like crazy to find that there was more in me."
Of F1's next generation after him, Piquet said: "The two at Force India look good, and those at Toro Rosso seem better than Buemi and Alguersuari."
Commenting on some others on today's grid, he continued: "Maldonado has always been fast but makes many mistakes.
"Perez has done a few good races, but we don't know if that's just because of the car. I think Button will be better than him at McLaren."