A freak training ground accident, a collision with then team-mate Abdessalam Benjelloun as he went down at the Moroccan striker's feet, left Stack partially sighted and his first season at Easter Road drew to an early close.
And having spent much of last season battling against a nagging back problem, the 28-year-old found his comeback brought to a shuddering halt after just five games as Hamilton Accies defender Mark McLaughlin sent him crashing to the turf at New Douglas Park.
Damaged ligaments in his right shoulder and a major operation was the result for the much-travelled goalkeeper who, having seen his appearances for the Edinburgh club strictly rationed, had been forced only days earlier to declare he wasn't injury prone.
However, as he prepared to visit the surgeon who repaired his shoulder for what he hoped would be the final time, Stack insisted injury was simply "part and parcel" of life as a goalkeeper and that he won't be putting his own personal safety first in future.
At the time of the sickening clash with Benji, Stack, who had been left with bleeding inside his left eye, a small clot on the pupil and inflammation, said: "I have been hit in the face countless times by football and kicked in the head countless times over the years.
"I am not one to shy away from a challenge. It's just the nature of the game and the nature of me, if the ball is there to be won I will go for it."
While that incident was seen as purely accidental, Stack hit by a combination of the ball and Benji's boot, the London-born stopper viewed McLaughlin's challenge on him on the night of the first day of March as containing more than a little intent, the goalkeeper hit in mid-air after collecting a cross.
If many view goalkeepers as receiving too much protection nowadays, Stack's painful experiences highlight the dangers inherent in playing that particular position, but the former Republic of Ireland Under-21 star remains unfased by the thought he could find himself imperilled again.
Admitting he felt as if he was "tempting fate" to some extent in engaging in a discussion about the travails he has suffered since being signed by former boss John Hughes two summers ago, Stack said: "It's the way I play and I am not going to change.
"I might have to take a sore one occasionally, but I can live with it. I'm not suddenly going to go out training or into a match worrying that I might get injured and let that influence whether I go for a ball or not.
"The minute you start doing that you aren't half the goalkeeper you are and, to my mind, you are far more likely to get hurt hesitating or going for things half-heartedly."
After managing just 22 matches in his first season at Hibs, the future was looking much brighter for Stack, the disappointment of crashing out of the Europa League at the hands of Slovenian outfit NK Maribor mitigated to some extent by a win on the opening day of the season away to Motherwell.
Unfortunately for Stack it proved to be his last until he took to the pitch to face St Mirren at the beginning of February, his return to action after finally overcoming the back problem picked up in training extended by the miserable winter weather.
Nevertheless, Stack's return coincided with Calderwood's side, threatened with the prospect of sliding towards a relegation dog-fight, putting together a run of five successive wins, leaving the goalkeeper with a record of having played in six SPL matches and won them all.
He said: "It sounds good to have a 100 per cent win record, but it kind of pales a bit when you realise it was based on just six games. We only won ten matches all season so I was happy that when I did play I was on the winning side.
"However, give me the choice between having played 35 games or a 100 per cent record in just six matches I'd obviously go for playing many more times than I did. It was without doubt the most frustrating season of my career.
"I was in position to be No.?1 with the chance to play in so many games, so to lose it through injury was very disappointing. The biggest disappointment, though, was for everybody at Easter Road: finishing tenth just wasn't good enough for a club like Hibs."
Last season was also different to many others Stack has enjoyed over the years in that Hibs boasted three goalkeepers in himself, Mark Brown, pictured left, and Graeme Smith, with Calderwood, after he had taken over from Hughes, opting to give all three the opportunity to prove themselves.
While Brown played in the vast majority of games, Smith was given a four-match run before Stack's unbeaten return appeared to have him marked out as the manager's preferred choice only for that injury to rule him out once again.
Smith is, of course, now gone, the former Rangers, Motherwell and Brighton man contemplating - as exclusively revealed by the Evening News - the prospect of continuing his career in Azerbaijan, leaving Stack and Brown to battle it out for the gloves.
Revealing he has his eyes on being fit for the visit of Celtic on Sunday, July 24, for the first match of the new SPL season, Stack insisted he's looking forward to that particular challenge.
He said: "It looks as if it will be Mark and I scrapping it out on a daily basis on the training ground trying to get the nod to play at the weekend.
"I am competitive - always have been - and I am sure Mark is very much the same, determined to pull that jersey on come the weekend. It's going to be a good battle, something to look forward to and I am sure it will bring the best out of me.
"Fingers crossed I can stay fit and make that jersey my own but you can be certain Mark feels the same way."