They need to beat Loyola next Saturday, which would mean they finish 13-5. They also need Valpo, CSU, and Milwaukee to each lose at least once. Obviously if Valpo and CSU win out, they would be 14-4. But also if Milwaukee finishes 13-5, Butler loses that tiebreaker. If they are paired with CSU, they win that tiebreaker. If they are paired with Valpo, the tiebreaker falls to common opponents, but Milwaukee will spoil that. If it's Milwaukee/CSU, then the tie isn't broken. If WSU beats UDM, then Butler loses that tiebreaker because Valpo swept WSU. If Detroit beats WSU, Butler loses that tiebreaker because Valpo is 4-0 against WSU/Detroit while Butler is 3-1.
So, Butler wins the #1 seed if:
1. They beat Loyola AND
2. Milwaukee loses at least 1 more game AND.
3. Valpo loses at least 1 more game AND
4. CSU loses at least 1 more game AND
5. If Valpo wins 13, CSU has to also win 13.