I'm not so sure about how impressive his career has been in the CTS and BGN series.
In CTS, he used to make some of the stupidest racing moves, one that they once called the McMurray move (except it was so dumb, they never got to use it again). McMurray was coming up on two trucks that were racing side-by side, and McMurray was racing on the top. Going into the turn, McMurray held on the gas and shot on the bottom of the track onto the apron to try and pass the other two trucks! He of course immediately shot right back up the track and right into the two trucks on his outside!!! The other two trucks hit eachother and the one went into the wall, but he was able to go on. Looked an awful lot like what Todd Bodine did tonight in the Cup race, except McMurray was able to keep it straight.
In BGN, McMurray was never that impressive until this season, where he got a 2nd place finish on fuel strategy, and then a second 2nd place finish that he actually earned.
That's been McMurray's career up to this Cup win. Now don't get me wrong, there's nothing wrong with him. He'a talented and very friendly driver. It's just you wouldn't know how well he could run until you put the right equpment under him. To say he was impressive in CTS and BGN is the overstatement of the century.