I actually never knew the build up to that match. Like why it was happening.
There's a bit on Wikipedia about it but, basically, they brought in Williams, 'Dr Death,' with a high profile but couldn't get him over with the fans. So they wanted to work him into a legit shoot-style angle to show how tough he was, but he got his arse handed to him by Gunn. Rumours are WWE execs didn't like it and hired Butterbean to stiff him at Wrestlemania as punishment.