Would Carlos Gomez, Adam Dunn, or David Ortiz be better players if they used the entire field? Some players don't swing that way. If they have the swing and the power to be dead-pull and do it successfully, I see no reason to change that. Oswaldo Arcia has just over 600 MLB PAs with an OPS+ of 100. He just turned 23 years old a few days ago. There's a lot more power coming from that swing as he matures and I think it's a mistake to force him into an uncomfortable plate approach. Work on his discipline, sure. Work on pitch recognition, definitely. Tell him to go oppo field? Nah, not so much.