I did some quick searching and couldn't find this report anywhere, can someone post a link please? Honestly I don't think this Rumble match winner is as easy to predict as we think. I thought I'd ask some people who are more casual fans who they think were going to win it and it was quite interesting what I got back.
First I asked my two close friends who are twins (17) and just started watching a month before SS and explained what the match was to them both and the importance and they said Ziggler. My dad (36) told me that he thought Ziggler would win too. One of my neighbors (14) thought Reigns would win. Another neighbor and his son next door (31 and 5) answered, they both said Ziggler but the kid said Cena too. I asked a couple kids at a football session I was running at the local park and five said Cena and three said Ziggler (their age group is mostly 9-13 year olds). Finally I asked a random kid at the gym wearing a CM Punk shirt so he was easy to spot and he thought Ambrose or Ziggler.
That means 9 answered with Ziggler, 6 with Cena, and then one each for Ambrose and Reigns.
I find this interesting because looking at how booking is going recently it does reflect the results I got. Ziggler has been booked strongest lately, and been playing the role of Cena 2.0, using Cena's signature move the kick out and winning in almost every match for the past few months. Cena has become himself again, with another win over Rollins on Raw after overcoming the mighty J&J interference. Reigns has been booked strongish, but I guess with him struggling against Fandango for a bit on Smackdown and just coming back from injury they didn't believe he was strong enough to win the match. Then finally Ambrose has been booked to lose quite a few matches recently, to a TV and a candy cane, so maybe that's had an effect on their support.
My point is that to us we may think Reigns winning is predictable and that Ambrose or Ziggler winning is a swerve, but to the majority of the audience in fact Ziggler winning could be what they expect, and Reigns or Ambrose might be a pleasant surprise win as long as a major heel like Rusev or Rollins eliminates Ziggler and not one of Ambrose or Reigns.
In my opinion now, I think Reigns and Ziggler are the front runners to win, and if Reigns can't get the crowd on side and sell some t-shirts then Ziggler will get it. Ambrose would then be plan B obviously, that is to say Daniel Bryan doesn't return at the rumble, in which case I think he'll win. But just like everyone else, I could be miles off the mark so these are just my two cents
