Based on KBO data, a direct move might be better for MLB success

Watching average 145 km/h four-seam fastballs in the KBO,
then seeing 150+ km/h breaking fastballs all over the minors, I feel like players need to adapt to that from a young age to stand a chance in the MLB.
Since there are almost no players throwing two-seam fastballs in the KBO right now,
the problem is that they'll have to adapt all over again once they get to MLB.