Andersp:  I'm sure you are not stupid, just pretending to be ;-)

If I lose to a lower rated player, it may be that he or she played better than I on this occasion, or because the dice favored him or her.  Similarly, if I win a backgammon match, it may be because of the dice or because I played better.  In chess, it's almost always a matter of skill, though there can be occasions I am sure when a player with less overall chess playing ability outplays a better player. 

The point about backgammon is that the player is only partly in control, due to the random element.  Thus, a rating in backgammon is not so much a prediction about the outcome of a single match, as it is a prediction about the outcome of a large number of matches.  Given a sufficiently large sample, the luck factor will even out and the player with greater skill will win a majority of the games.

My BKR is the result of a mathematical formula being applied to the results of my games.  Some of those games were won or lost primarily on skill, others on luck.  I offer no conclusion as to the interpretation of the backgammon BKRs on this site.

I hope that clarifies it, in case you were not just pretending ;-)