Everyone loves a good underdog story after all. A good trip abroad can always help you get the experience you lacked or look at things from a different perspective, being involved with new people always does that.
Since Mikolas did both things, he went to a new country and new people, new league, new everything, 3 years was enough to find a new course for his baseball career! I'm pretty sure everyone knows the Japanese solve every problem with discipline and hard work that might have helped him a lot too.
That's a good point. Living abroad in a different culture certainly provides some perspective on life and one's place in it, completely apart from any athletic skills.