It doesn't have to mean they have been fired. The most common reason is that their contract has ran out and hasn't been renewed due to the fact they want to leave or that there too old and no longer required.
Ty Murray Michael Gaffney Jim Sharp Jerome Davis Ted Nuce Troy Dunn Cody Lambert Cody Custer I think are some
The website I know that gives true information because I sent a letter, got it back and many other people did. This is through it's www.fanmailbiz.com
In seats filled,TV etc. in one setting it would be the Indianapolis 500, I used to watch, go there, but for me its not as exciting as Nascar.