Yet within a month, O'Connell had inspired Munster to a Heineken Cup win over Harlequins and made such a compelling case for inclusion that bookmakers made him odds-on favourite to captain the touring side for the second time in a row.
While the captaincy went to Wales' Sam Warburton, the big second row's selection was never in doubt from the moment the full time whistle sounded at The Stoop and O'Connell, hand raised in the air, was mobbed by his team mates.
"Three months ago, I didn't think I'd be here so it's all a bonus for me," O'Connell told reporters at the Lions' Irish training camp on Monday.
"People ask me would I have been disappointed if I hadn't been selected, I wouldn't have been really. I got back from a very serious injury as quick as I could and played as well as I could. When you give everything you have, if you come up short that's just the way it is."
Dogged by injury since he led the Lions in South Africa in 2009, the 33-year-old underwent surgery on his back for the second time on New Year's Eve and all but ruled himself out of Lions selection 10 days later.
The Harlequins' game, with O'Connell dominant in the lineout and immense in the loose, changed all that, yet conscious that he last started for Ireland over a year ago, the 1.98-metre tall lock was unsure if he was even in Warren Gatland's thoughts.
"Up until my name was read out, I wasn't sure. It was hard to know having not played any international rugby since last March and very little rugby since the previous May, it was very difficult to know if they were even going to consider me.
"I just tried to avoid the speculation. Someone would play a good game one week, they'd have pencilled themselves in for the tour. They'd play badly the following week, they'd have written themselves off and they'd play well the next week and they'd have pencilled themselves in for captain."
Four years on from his last time in the red of the Lions, O'Connell says he is far more relaxed, not least because the captaincy duties rest with Warburton, whom the 85-times capped Irishman roomed with last week.
The former captain described the current tour's lieutenant as wise beyond his years, recalling that at 25, a year older than Warburton is now, he was a lot more naive when he toured with the Lions for the first time in New Zealand in 2005.
He said he has not offered the Welsh skipper any particular advice, but does recommend that some Lions traditions continue.
"Hopefully we'll get a few nights out, I know we've gone very professional but I think there's a point where professionalism has a certain amount of limited gains," he said.
"You do need to be a little bit old school at times and get a night out or two. I'm not sure has Warren pencilled that in, I'll let Sam have that chat with him."