Carter didn't loose because he lost the debates. He lost because he was the worst President in 30 years with double digit interest rates, soaring unemployment, High gas prices with lines, loosing control of Iran and waiting 11 months to even attempt to rescue the hostages held in Iran after the Shah fell and then botching it. etc etc.
Well, yes, but if the polls are to be believed he would've still won had there been no debate.
Not to mention it was his fault the Shah fell.