pitching is a lot better in the states, they also utilize analytics/LOOGYS/shifts more here.
most batters do far better against opposite handed pitchers, Ohtani is so far part of that group until he proves otherwise.
Just like until Bellinger proves he can hit that curveball he deserves to see it over and over. Managers will utilize the situational left handed reliever against Ohtani every chance they get and he has to make adjustments to prove he can handle those types.