Who's saying anything about dropping Stevens or playing Coleman or Doherty at CB?
Several good CB options? Realistically we have two - Clark and O'Shea. Duffy is very droppable - Kenny axed Coleman for less.
But I think I know what has you flapping like a bat in a belfry. Here goes - Doherty is very capable of playing (and scoring) from midfield or wing back in 442 or 352. He'd definitely be better than Cullen, Browne, Molumby or Curtis et al in such a crucial game. That's not experimenting - it's setting out your team to suit your best players.