He has not added to his two grand slam titles since and the 29-year-old split with coach Amelie Mauresmo this year.
"I think clearly my old rival Ivan Lendl made a positive difference with Andy," the American told the Daily Telegraph.
"I am not sure if the baggage that took place when they broke up... I don't know if that was really mutual or if it was Andy or Ivan. I don't know if it is like going back out with your ex-wife or ex-girlfriend.
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"But it would not surprise me and it might even make sense. It might not work. But it is an interesting thought."
Murray currently has former British player Jamie Delgado in his entourage, but many of the top-ranked men work with so-called 'super coaches'.
World number one Novak Djokovic has six-times major winner Boris Becker in his corner, Kei Nishikori works with former French Open champion Michael Chang and Milos Raonic will tap into McEnroe's grasscourt knowledge for Wimbledon.
Even 17-times grand slam champion Roger Federer has gone down the same route, previously working with Stefan Edberg.
"It's been a win-win for Boris and Novak," McEnroe said of Djokovic's partnership with the German.
McEnroe even said he would have been interested in working with Murray.
"Andy is extremely professional. He won a couple of majors. So you're talking about the cream of the crop," he said.
"When you look at someone who's that good, you're always interested... (but) I don't recall ever getting a call. There was never any discussion."
Murray, who reached his first French open final last week where he lost to Djokovic, appears to be in no hurry to recruit a new coach, but McEnroe believes the world number two could look at bringing in someone to work with Delgado.
"I mean he has got Delgado, so he has a coach, but he might want to bring in a second guy -- the 'looking for some extra attention' guy. I fall into that category too, by the way -- that was my attempt at a joke," he added.
(Writing by Simon Jennings in Bengaluru; editing by Martyn Herman)
