I don't know about the other bowls. But for the Rose Bowl it is the poll they use to justify their selection if a conference's champion is in the playoff.
"Should a team from the Big Ten or Pac-12 be selected to go to the College Football Playoff, the Tournament of Roses will traditionally select the next-highest CFP-ranked team from that conference. There is, however, a caveat to that clause in the contract.
'If the next-highest ranked team is in a ‘cluster’ of teams, meaning there is another team or teams from the same conference ranked within several spots of each other, the Tournament of Roses will select the team from that cluster that will result in the best possible matchup for the Rose Bowl Game,” said Rose Bowl Management Committee Chair Scott Jenkins.'
Though they end with this statement -- "It should be noted that it is the strong preference of the Tournament of Roses, Pac-12 and Big Ten Conferences, that the highest-ranked available team in each conference be selected as the replacement team."
The selection process for the Rose Bowl Game has, in a sense, gotten easier in the College Football Playoff (CFP) [...]
tournamentofroses.com