The nice advantage Neris has is because he has such a good and deceptive splitter he can sometimes get away with a fastball in the zone. If the hitter is looking for the splitter he will take the fastball right down the middle thinking it will break out of the zone (or if he just reads it wrong). Still, better to not throw the pitch that fat, but he has a better chance of getting away with it than most, and every pitcher does it sometimes.
Neris a funny guy to me. He has some really good stuff and then a relatively flat, straight fastball. I have no idea if they can do anything, but I was always taught to just move a finger a little on the ball and you will get a little motion (at the cost of a little speed). I assume they have tried that with him, not sure why it doesnt work. He needs that motion on his fastball, and if could move away from RH hitters that would be best, but towards them would be ok. He just needs motion different than his plus plus splitter.