WWE wanted to protect Ryback. They used them because everyone else already competed last night and it is easier to write the motives of new characters than transform older ones. Don't read too much into this.
I was convinced Dean Ambrose was meant to debut at Wrestlemania and defeat The Undertaker in the first of 22 consecutive matches right there, winning them all to go 22-0 @ 'Mania before telling Vince McMahon to suck his 3 foot Kane dong right there and single handedly restart the attitude era before delivering the highest TV audience since the moon landings on Raw the following night, a night brought on by him clenching his ass cheeks to hide the sun from shining out of it!
It appears as if CM Punk and/or Heyman are behind some sort of Nxt invasion, the Newest Nexus if you will. Tired of copying TNA WWE are now copying themselves! It's too early to judge but if after last night Seth Rollins and Dean Ambrose are a part of the main roster that's a good thing and if they're half as good as the IWC claim they'll find their feet just like Daniel Bryan, Antonio Cesaro and Damien Sandow have.
(Please take all but the last sentence with a healthy pinch of salt, I'm joking!)
Wrestlemanina 52: (22-0) Dean Ambrose vs (22-22) 90 year old Undertaker.