Just five weeks into the season, the undefeated field has dropped from 136 to 20. Last year, Oregon was the last team standing, going perfect through the regular season and the conference championships until a loss to Ohio State in the CFP quarterfinals.  Here are some of the undefeated teams to watch in Week 6: *Undefeated team is bolded     No. 11 Texas Tech at Houston, 7...