I think one reason that it is more important for Arcia to learn to use the whole field is that he apparently has no clue where the outside of the strike zone is and, from his career W:SO rates, it looks like he never has. This is quite different from many of the other sluggers that have been listed (Willingham, Ortiz, Dunn, etc). Until he learns either better strike zone judgement or to drive the ball the other way, he will continue to be a low BA, sub-.800 OPS guy. That is not to say he wouldn't still be a very useful player... Jacque Jones never did learn how to hit left-handers or lay off sliders in the dirt and was an integral part of our success in the millenia's first decade!