A 5th year player is "battle-tested" against other collegiate athletes for 4 years and is at the peak of her athletic and lacrosse abilities. She is only a 1 year commitment, which could also be a good thing.

A HS school is recruited solely based on a future projection against fellow HS students.. She will not arrive on campus for 2 years.
She realistically won't be able to contribute and help her team for 3-4 years. Of course, coach's projection of this prospect is only a guess.
She may not meet lacrosse expectations. She could become an academic risk. She could also become a 4 year headache with her teammates and coaches.
She could even drop out of the team or transfer somewhere else. Assuming she even meets their highest expectations, the coach who recruited her may no longer be around to reap the benefit.