The album has a bluegrass or progressive bluegrass core ; bluegrass mandolinist Ronnie McCoury became the album 's official `` bluegrass guru '' to ensure that there was `` someone who could make sure we did n't do anything clichéd or trite '' .
Bluegrass mandolin player Ronnie McCoury became the album 's official `` bluegrass [ guru ] '' to make sure that there was `` someone who could make sure we did n't do anything [ clichéd ] or [ trite ] '' .