Traditionally, WrestleMania's headline matches are reserved only for the most popular - or "over", if you prefer - wrestlers in the whole of WWE.
But it hasn't always worked that way in practice. While fan reaction usually determines how far up the card a given performer is allowed to climb, there are other factors that sometimes come into play too. Factors like Vince McMahon just really liking someone whom you regard with complete indifference.
As such, there have been several wrestlers cast in the role of leading man on the Grandest Stage of Them All who perhaps didn't really get there entirely on merit. That's not to imply that they weren't talented - or even unable to garner some form of reaction - but simply that their credentials as crowd-pleasers don't really hold up next to the very best.
To be fair, though, in many of these instances WWE management has simply plumped for what was - or at least what they believed to be - the most lucrative possible match-up in a given year. From a business standpoint, you can't really argue with that, although we're still going to try.