I actually think it is bad news when he hits a home run. Now to explain, my ridiculous statement. His swing on the best days is too long. After he gets one, its gets longer. The guy could ground ball his way to .260, if he stopped trying to hit everything 420 feet.
Well, that's the mentality of hitters in general today but with Mateo, he just has such a poor awareness of what is a strike or ball that you really can make him look like a fool at the plate. If I was a pitcher, I would never throw him a strike because no matter how far off the plate the pitch is, he's going to swing anyway. Just a clueless hitter with speed.