Sample statistic: assuming that your opponeng is chosen with a RNG, you mast play 1497 match in Arena to have 95% chance to meet your deck (of course you must always face the league where your deck is).
It also happened to me, back when I was in gold league last month, I faced my deck and decided to skip the match, resulting in a 10 coin loss (15, but 5 earned by deck), but rating increase for my deck...