Its the whole bigger faster stronger thing.
Plus its mental. The lower team sees the higher team score with two hits followed by a homer and think its easy but when they go to do it they don't and then the score starts to pile on mentally. Then they decide to go back to base hitting and realize their averages on base hits goes down against major teams because they have better defenses.
But there are many players and teams in the conference that learn to get past this and compete with the major teams on a regular basis, but it takes mental toughness and experience.