Trapattoni has his loyal lieutenants such as Glenn Whelan and Sean St Ledger and Declan Kidney is no different.
In the protracted absence of Jerry Flannery, Best has been Kidney's preferred choice at hooker, even when short on game time, as happened in the run-in to the Italy match. The Ulster captain is an old-fashioned, nuts and bolts hooker with a strong scrummaging reputation, but lacks the ball-carrying verve of Sean Cronin and Damien Varley.
Excellent against Italy, but was deemed lucky to get selected ahead of Leo Cullen, who did superbly in O'Callaghan's absence at the start of last year's Six Nations only to give way as soon as the Munster man was fit. Both are quality second-row operators.
One of the most physical and defensively proficient scrum-halves in the game, O'Leary has been first choice for Kidney. At his best, his all-round game is top-drawer but when he struggles, as he did against Italy, his slower delivery becomes a disadvantage. Eoin Reddan and, especially, Peter Stringer provide speedier service to give the outside backs more time, but they don't have the same defensive capabilities.