Complex sentence: The poll was created in the summer of 2005 to replace the AP Poll, which decided it no longer wanted to be a part of the formula used by the BCS rankings to determine who plays in the BCS National Championship Game.
Split into simpler sentences: The poll was created in the summer of 2005 to replace the AP Poll in the BCS formula. The AP had decided it no longer wanted to be a part of the formula used by the BCS rankings to determine who plays in the BCS National Championship Game.