Excellent post Steve4192. Good points.
Ervin...let's start with the positive. Dramatic improvement in center field...now looks like a guy who won't hurt you there, which is a sharp contrast to where he was last year and early this year....has tremendous bat speed, so when he makes solid contact, the ball is going to go somewhere in a hurry...has much better power than the home run numbers imply...can hit a good fastball.
On the other hand...long way to go as a hitter. I asked four scouts last night if they were turning him in on their report as an everyday player and none of the four said they were. He doesn't just chase sliders out of the zone, he struggles with breaking balls in the zone. Any breaking ball on the outer half of the plate is a problem because he takes a huge, dead pull swing. You move him up right now to face pitchers with good command of their breaking ball and he will get absolutely embarrassed. His speed is overrated. I would say he is an average major league runner. His timed speed to first is actually below average because he takes such a big swing that he is slow out of the box. Needs to learn to hit the ball to all fields. Does not have a standout tool. I am not crazy about his makeup, but he does play hard. Seems to be a guy who has never really been pushed and does not react well to criticism.
All that being said, don't give up on him. He could still become a useful player if some things go right.