After the disappointment of finishing fifth in their 2014 World Cup group it would hardly have been surprising had experienced performers such as Aaron Hughes, Gareth McAuley, Chris Baird and Roy Carroll exited the international stage.
But while results were disappointing in his first campaign, O’Neill had improved and modernised the entire environment around the national side and the quartet were persuaded to stick around. Each has gone on to play an important role in qualification.
The lack of a regular goalscorer was O’Neill’s biggest conundrum when he started work in 2012, with David Healy’s remarkable run almost at its end and his most likely heir, Kyle Lafferty, frustratingly inconsistent.
He did not find the net once in O’Neill’s first campaign and O’Neill delivered some unvarnished home truths after Lafferty was sent off against Portugal shortly after being brought on.
But that frank talking, followed later by an arm around the shoulder and a second chance, set the striker on his present path and he now hails O’Neill as the best manager he has worked with.
Northern Ireland’s player pool is small, making it hard for bosses to pull rabbits from hats when it comes to selection.
But O’Neill has made mainstays out of a trio of players who had been on the periphery of predecessor Nigel Worthington’s squad – Oliver Norwood, Jamie Ward and Conor McLaughlin.
Prior to O’Neill’s arrival their senior international careers totalled a matter of minutes combined, now all three look comfortable on the big stage and are inked in as starters at the European Championship.
O’Neill’s first assistant was Scotsman Billy McKinlay, a savvy, serious-minded coach who helped set the template. When he left, O’Neill leant on the experience of Jim Magilton and the youthful but well-qualified Stephen Robinson before naming two-time World Cup veteran Jimmy Nicholl as his permanent number two.
Maik Taylor also arrived as goalkeeping coach, completing a respected group of former Northern Irish internationals to guide to current generation.
O’Neill’s judgement in each case has proved sound.
Northern Ireland started the road to France with an atrocious recent record on the road. In fact, they went 18 consecutive matches without a win away from Windsor Park – a stretch that started with Nigel Worthington and carried on in O’Neill’s first two years.
But redevelopment work at their home stadium saw the side rack up 34,000 air miles in a sequence of seven successive away games in a nine-month period.
Somewhere along the line a formula was found and the team have beaten Hungary, Greece and the Faroe Islands on their own turf in Group F.