I know that everyone goes through slumps at the plate but from the games I've watched Markakis appears to make some really poor choices at the plate. In particular I've seen him swing at a lot of breaking balls in the dirt on 0 and 2 and 1 and 2 counts. Most major league pitchers won't throw you strikes in those kind of counts if they don't have to.
I know he hasn't had a horrific beginning of the year by any stretch but I feel like he really isn't seeing as many pitches as I would expect from a veteran hitter with a good eye. When he came up I remember the knock on him being that he was almost too patient at the plate and that the O's wanted him to take more chances and swings. Maybe he took that too much to heart.