When I first saw this, I figured de Aza was just being a dope and digging in... but then DD was quoted as saying things that sounded to me like the O's began by giving him a take-it-or-leave-it offer... which seems kinda provocative to me... I'd think you'd leave a little wiggle room in there, just to show that you're a little bit flexible... unlike DD, I don't see the benefit of being rigid about it right out of the box...
From reading Duquette and Showalter's quotes on the subject I'm guessing there was a bit of acrimony with De Aza's agent and they decided to play hardball with him. It looks ridiculous. The smallest difference and this is the one that's going to arbitration.