The "Who do you think won the debate" question is alright I guess.
Maybe if most people didn't watch the debate.
I wouldn't be surprised if only one in Three or one in four Democratic primary voters actually watched the debate, Perhaps even less than that. 15 million viewers aren't all that much after all, and many of them were probably either Republican or independent.
Debates themselves aren't very important. But the video clips they provide that are played on the news or youtube for the next few days are important.