Xbox can be a source of entertainment, but it can also become an addiction. If that is all he wants to do, it will get in the way of everything. Practicing baseball will be the least of his problems.
Most people are best at the things they most enjoy. I bet he is very good at Xbox. Wonder what would happen if he were "forced" to play Xbox for 8 or more hours every day? Would he love it or hate it?
Not sure if you can get the best possible results by forcing someone to do something they don't want to do. Pushing someone who already loves the game is another story, that can actually work.
Here is my uneducated opinion... If you want him to work harder at something, try to create interest. Rather than suggesting he go hit, ask him about hitting. Ask him what he thinks about players and the game. Make him feel like he really understands the game. In other words, see if you can find a way to get him to love the game. Because if he ever gets to loving the game, you won't ever have to push very much. If your efforts fail and he never loves the game, his chances for success are so low it's probably not worth your time and effort.
Anyway, there are so many things that are so much more important than playing baseball. However, playing Xbox is probably not one of those things. Simply being a good person is one of those things. Best of luck