John McEnroe is a great commentator. He’s got the latest gossip and he’s packed with history. But my favorite part of his work is his ability to blast out a strong opinion about a tennis player’s game and give you food for thought for a long time.

For example, he would question Djokovic’s decision to switch from Wilson to Head and even suggest that his game slipped as a result. He would call Andy Roddick a “one trick pony”, maybe because of his huge serve, but lack of follow up aggression and diversity through the rest of his game. Such comments are not only bold and daring, but also help me take a side and shape my own opinion.

The flip side of such open commentary though, is what I wonder – can players “hear” those comments real time, as the match progresses? Is it possible that live coverage TV comments affect the outcome of a tennis match?

If McEnroe says “he’s gonna have to dig really deep to get out of this”, or “Federer looks clearly in control of this match” and the crowd in the stadium heard that comment, wouldn’t their faces change? What about their body language or behavior? The things they say during breaks, the whole crowd rumble, chatter or other white noise, or lack of it? Wouldn’t that affect the players on the tennis court?

I remember one time Federer’s dad was on camera as McEnroe introduced him to the TV audience. Fed’s dad was wearing one of those radio headset and he could hear McEnroe, so he politely waved at the camera. That was cool. Real time interaction! Takes us right into the game.

But what if the camera was on someone’s coach, and McEnroe said “I don’t think your guys is coming back after the second set…”. Wouldn’t that kill the mood a little bit for the coach and consequently for his player?

OK, maybe not everybody in the crowd has a radio headset with the streaming broadcast coverage the US Open had for American Express members. But even if their coach or fan booth heard those comments, whether through a radio headset or a mobile device, they might still communicate them, though non-verbally, to their player next time he looked at them.

That’s what I call the “commentator effect”. The possibility that a commentator might influence the outcome of a tennis match with their commentary.