Complex sentence: While managing the Angels, he once held a practice in the lobby of his team's hotel using only wiffle balls and bats; the point was to demonstrate that his hitters were so weak, they could not break anything in the lobby.
Split into simpler sentences: While managing the Angels, he once held a practice in the lobby of his team's hotel, using only Wiffle balls and bats. His point was that his hitters were so weak that they wouldn't break anything in the lobby.