Having watched most of Atletico's games to believe Courtois, who got himself utterly needlessly red carded only yesterday, makes no mistakes you are entirely wrong.
Secondly, Arsenal don't own Courtois, I never claimed he was better in the last two years. Saying Courtois is better isn't the same thing as saying Cech is a BAD keeper, being less good than an exceptional keeper isn't automatically terrible. The only relevant comparison TO ARSENAL, is who is better out of Cech, Chesny and Ospina. The reality is it's likely to be Cech and likely better than any other keeper we could get at the same price.