Abreu could be a perennial monster hitter if he copies Casas with regards to plate discipline. As of now he has a pretty good eye at the plate.
He has power, can run, a good arm, and so far can catch the ball.
He was lost in spring training and when the season started. Hopefully he is coached properly.
I don't think Valdez will get better as a hitter, but it seems his defense has improved.