Having seemingly overcome his 'first lap nutcase' troubles of 2012, 27-year-old Grosjean is now back in the wars with a ten-place grid penalty for Montreal for his Monaco crash with Daniel Ricciardo.
In the wake of the Monaco controversy, team boss Eric Boullier answered "not yet" when asked if Lotus might consider replacing Grosjean with GP2 champion Davide Valsecchi.
He and team owner Lopez, however, have also defended Grosjean.
"The first (Monaco) accident in practice was our fault," Lopez told Germany's Auto Motor und Sport.
"The tyre pressures were wrong and we did not tell him. The second crash was comparable to Massa's -- we believe both were distracted by a car coming out of the pits.
"From that, he was under pressure for the rest of the weekend. The speed was there," said Lopez, adding that hurried repairs meant Grosjean's car was "not really perfect" for the race.
And Lopez said the crash with Ricciardo was caused by frustration.
"Romain is not a guy who can drive behind for so long, especially when he knows he could be so much further forward," he said.
He said Lotus continues to believe in Grosjean, but smiled as he likened him to a talented football player "who is constantly getting stupid injuries".
"He's super fast in anything with four wheels -- he would be quick with a shopping cart.
"He is a natural talent and there are not too many others like him; Hulkenberg, Bianchi but I can't think of many others," said Lopez.
Meanwhile, Grosjean said he believes his ten-place penalty for the Ricciardo crash is "quite harsh".
As for his mixed 2013 season so far, he said: "On paper it's not as good as we would have wanted it to be, but I'm happy with all my performances so far except for Monaco."