Yes, too many bad bots will push not-bad players a bit higher -- but that isn't a huge problem unless the ranking system also has an upward trend.
Also, yes, the bots are bots -- but some of them are programmed well enough that they are legitimately in the top 50 (even though there is also an obnoxiously huge number that play terribly and have only first level decks to boot -- which don't require much skill anyways).