Okay, let me try to explain it to you:
Crew 1 vs Crew 2
Crew 1 has 5 members.
Crew 2 has 4 members.
The least common denominator (I hate math) of 5 and 4 is 20; therefore, each crew gets 20 stocks.
The battle begins.
Match 1: Crew1Player1 (4 stocks) vs Crew2Player1 (5 stocks)
Let's say that Crew1Player1 wins and has 1 stock left, he starts the next match with 1 stock against a fully stocked opponent.
Match 2: Crew1Player1 (1 stock) vs Crew2Player2 (5 stocks)
Let's say that Crew2Player2 wins and has 4 stocks left, he starts the next match with 4 stocks against a fully stocked opponent.
Match 3: Crew1Player2 (4 stocks) vs Crew2Player2 (4 stocks)
Let's say that Crew2Player2 wins and has 1 stock left, he starts the next match with 1 stock against a fully stocked opponent.
Match 4: Crew1Player3 (4 stocks) vs Crew2Player2 (1 stock)
Let's say that Crew1Player3 wins and has 4 stocks left, he starts the next match with 4 stocks against a fully stocked opponent.
Match 5: Crew1Player3 (4 stocks) vs Crew2Player3 (5 stocks)
Let's say that Crew1Player3 wins and has 2 stocks left, he starts the next match with 2 stocks against a fully stocked opponent.
Match 6: Crew1Player3 (2 stocks) vs Crew2Player4 (5 stocks)
Let's say that Crew2Player4 wins and has 4 stocks left, he starts the next match with 4 stocks against a fully stocked opponent.
Match 7: Crew1Player4 (4 stocks) vs Crew2Player4 (4 stocks)
Let's say that Crew2Player4 wins and has 1 stock left, he starts the next match with 1 stock against a fully stocked opponent.
Match 8: Crew1Player5 (4 stocks) vs Crew2Player4 (1 stock)
Let's say that Crew1Player5 wins and has 2 stocks leftover.
The Crew Battle is over because Crew2 lost all 20 stocks to Crew1. Crew1 wins by a score of 2-0 because Crew1 had 2 stocks at the end of the battle and Crew2 had 0 stocks.
Does that help at all?