Something that I have come to conclude as well. Nobody wants to be on the end of a 0 - 9 and there is a lot of pain and soul searching that has to take place when it happens. But on reflection, I tend to agree with you. At the time, Leicester were flying and second in the league I believe, so after the sending off, had we lost 5, even 6 nil, perhaps it would've been put down to a 'bad day at the office' , file 13 and move on.
But because the score was so embarrassingly bad it forced us to have to take a long hard look and reflect on how we needed to change things. I was at the game 3 days later at the Etihad and you could see that there was no confidence whatsoever and nobody really wanted the ball, we needed a complete rebuild in that regard. Let's face it though, we were never a 9 nil team, yes we were bad, but not that bad...! The 9 nil, did two things, it set the bar really low, and meant that realistically we could only get better - it was the almighty kick up the 'arse that we needed this season. Don't want to experience it again - but the club, manager and players took a massive negative and turned it into a positive over the remaining course of the season.