Kelly has made his name as a full-back but can play across the back four, while McShane has lined up on both the right side and in the middle of the defence during his career to date - and that versatility could prove key at Euro 2012 with John O'Shea and Darren O'Dea nursing injuries and Richard Dunne and Sean St Ledger also suffering niggles.
As a result, both Kelly and McShane are happy to be considered for multiple roles, and the 28-year-old Fulham defender said: "If the manager was to ask me to play anywhere, I would do it - and gladly do it - and give 100%. I think I can fill in and do a good job there."
He added: "I feel comfortable anywhere across the back four, and that's been of benefit to me in the past. I have played in every position across there."
It was precisely that kind of adaptability which earned 26-year-old McShane his last-minute call-up to Trapattoni's final 23 in place of the unfortunate Kevin Foley.
He said: "I can play both positions. I feel comfortable there, and I can play right-back also, whatever is needed, really.
"If there is an injury or whatever, I am ready to step in."
The Ireland squad had a day off on Wednesday as they came to terms with Foley's surprise exclusion, and while McShane felt for a man with whom he played at Under-19 and Under-21 levels, he now has to prepare himself for the heat of tournament battle.
Trapattoni confirmed on Tuesday night that the Wolves full-back's exit had nothing to do with the hamstring injury with which he had been struggling for the previous week or so, and everything to do with his replacement's ability to cover the central defensive positions.
Ironically, it was the latter who missed training the following day with a heel problem, although one which ultimately did not prevent him from playing in the 5-0 friendly victory over a Tuscan Select XI.