Both consider themselves lucky to be alive, let alone featuring in Ireland's World Cup adventure which begins against the United States at Lansdowne Road on Saturday evening. With all due respect to Davidson, O'Kelly's close shave was the more dramatic.
At a break from a training camp at Swansea University with Leinster, O'Kelly went swimming off the Mumbles coast. "I was on a rock and we were all just messing about," he said. "I was coming out of the water when a huge wave - I didn't even see it - hit me from behind and took me back out to the sea. I was panicking and thinking: `This is it. The end'. I was getting bashed against the rocks then taken out again. It didn't matter how strong I was.
"It happened so quickly. The lads saw me but the rocks were so sharp it was very difficult to move quickly and there was very little they could do. It was up to me and after a while I completely panicked. Finally I got it together and told myself: `I'm not prepared to go right here. There's plenty more in me.' Maybe the World Cup ambition was driving me. The waves calmed down again and I was able to swim back ashore.
"There were no flags warning against swimming. It was just a complete freak. I swallowed a fair bit of water. When my feet touched the ground again I ran up the beach as fast as I could. I read in the papers the next day of how a guy died trying to rescue a swimmer in the same area on the same day."
Davidson was the unheralded Irishman who went on the Lions' tour to South Africa two years ago and monopolised the lineout. No sooner had he returned to London Irish than he damaged a cruciate knee ligament which put him out of the game for a season. However, the consequences of the operation were nearly far worse.
"I reacted very badly to the anaesthetic," he said. "They later discovered I was allergic to it. I was put on a ventilator and things were quite critical at one point."
O'Kelly and Davidson, who are 25, were both released by London Irish, the former to his old club St Mary's College, the latter to Castres. The French club made Davidson an offer he could not refuse, believed to be pounds 200,000 a year.
Last season was O'Kelly's turn to be injured and he missed the entire Five Nations, a championship which held huge promise for Ireland but which again ended in anticlimax.
Both locks are back to their best and with the former captain Paddy Johns also on active duty, the coach, Warren Gatland, is spoilt for choice in at least one position.
When he announced his team to face the American Eagles - the same 15 that recently beat Argentina - Gatland admitted: "Our biggest debate centred on the second row." In the end he plumped for Davidson and Johns with O'Kelly on the bench although Gatland added that the latter would take the field "at some stage".
O'Kelly, the son of an engineer who played in the second row for St Mary's College, was born in Chelmsford and the family moved to the Netherlands and Limerick before arriving in Dublin. An Essex man he is not. Malcolm Eamonn O'Kelly is as Irish as Molly Malone although about five times as big.
His progress at London Irish under Dick Best earned him his first cap against New Zealand in 1997, but when his contract at the Exiles expired in the summer they could not agree terms.
Ireland have fallen in the quarter-final in the previous three World Cups, twice getting knocked out by Australia, who are in their group this time. "I think we can go further than any Irish team has gone before," O'Kelly said. "We've got some new players who are very talented, we are at home, we've got a good draw and we're the underdogs and you know how Ireland react when they're written off. If we can get on a roll it will be interesting. Once we've built a momentum we could become unstoppable. It's scary."
Not half as scary as believing you are about to be washed up by the cruel sea.
IRELAND (v United States, Lansdowne Road, Saturday, 7.0): C O'Shea (London Irish); J Bishop (London Irish), B O'Driscoll (Blackrock College), K Maggs (Bath), M Mostyn (Galwegians); D Humphreys (Dungannon), T Tierney (Garryowen); P Clohessy (Young Munster), K Wood (Garryowen), P Wallace (Saracens), P Johns (Dungannon), J Davidson (Castres), T Brennan (St Mary's College), A Ward (Ballynahinch), D O'Cuinneagain (Ballymena, capt). Replacements: R Nesdale (Newcastle), J Fitzpatrick (Dungannon), M O'Kelly (St Mary's College), E Miller (Terenure College), B O'Meara (Cork Constitution), E Elwood (Galwegians), J Bell (Dungannon).Reuse content