Why cant i hit as far in real games?

ok so a couple days ago i was playing baseball with my family at a family reunion and i was usin the same bat that i use in my real game but at the family reunion i hit 2 balls really deep into the outfield. the balls were goin alot slower but whenever i m,=ake contact in a real game there always grounders. is it just because the ball was goin slower? if it helps i use an easton stealth bat.