Look it's fairly obvious now that Casey has more poise, confidence and is better at managing the game than Card at this point. But, Sark was evaluating these guys from practice and a Spring Game. It was reported to be a very close call and an extremely tough decision. Sark supposedly went with Card based on his ability to go through his progressions faster, which enabled him to get the ball out quicker and his ability to make accurate throws on the move when things broke down. Card just isn't there yet mentally, might never be, who knows.
It's clear now Casey is the starter, but even after the UL game it looked like Card was going to be the guy. You can make the argument that Sark should have pulled Card earlier in the Arkansas game and he probably should have, but I think he was trying to see if Card had settled down after halftime.
Posters claiming Sark made a monumental blunder by going with Card is just fucking stupid. But overreaction is what we do, so carry on I guess...