I agree. He passed the Mendoza line a long time ago. Even his most staunch supporters (you can throw me in there) are running out of patience.
He's adopted a very unorthodox set up at the plate... Not always, but plenty of times he is still shuffling his feet while the pitcher is in his windup so that by the time the ball is in the strike zone, Miggy isn't even close to being ready to swing...
He's always been prone to taking wickedly aggressive swings as if he's going for the fences with each at-bat, but, in the past he was typically able to check that and take a slower, smoother swing when he just wanted to make contact and drive the ball into a gap. But now, there is nothing smooth or slow about his swing at all, ever. He looks totally out of sync. He very rarely ever puts a professional looking swing on the ball, and he is constantly taking meatballs for called strikes, while swinging at bad pitches.
This could go down as a huge mistake by the Dbacks in locking him up to a longer term deal. It's almost as if Miggy needs to be sent down to Reno where he can make an effort to find his swing, while not hurting the team. But of course, after signing him to his new deal, there really is no chance of him going to Reno... Not good... :-(