I think you over-rate Varley. He's done a solid job in Jerry Flannery's absence but he's part of a poor scrummaging unit, his lineout throwing is iffy and he goes to ground too easily when he's carrying the ball. Maybe that's a harsh assessment but it rings broadly true.
The other options available to Declan Kidney are hardly perfect either. Flannery is the best thrower of the lot and is dynamic in the loose but can't stay fit and is ill disciplined, Cronin is a brilliant carrier in space and a decent scrummager but he's got dodgy hands and his darts are very shaky while Best is the best scrummager of the lot, is a leader and he defends well but he's not an explosive carrier and his lineout throwing has gone to ****.