A 3-0 thumping in Braga was the Welshman's baptism under fire as the Hoops' hopes of negotiating the qualifying rounds of the Champions League were ended before they had really begun.
Losing to Utrecht after parachuting – or plunging – to the knockout round for a Europa League place meant Europe was over for the entire season.
What a contrast to today as Neil Lennon's side use their Marbella training base to put the finishing touches to their preparation for the second half of the season, which includes a Champions League last-16 clash with Juventus.
The dramatic progress made in this very short period of time – enough to help them defeat Barcelona – has earned praise around the Continent.
But it has also robbed Celtic of one of their secret weapons which could have been deployed against the leaders of Serie A – the element of surprise.
Although Juve are short-odds favourites to dispose of the Hoops and march on to the last eight, and a steady procession of ex-Juventus stars – including Uefa president, Michel Platini – believe that the draw virtually guarantees the Italians safe passage in a competition they are considered to have a good chance of winning at Wembley in May, no one at the club nestled at the foot of the Italian Alps is taking anything for granted.
Barca bombing at Parkhead to goals from Victor Wanyama and Tony Watt has made sure of that.
The fact the first leg is to be played at Parkhead, on February 12, is another disadvantage the Hoops must overcome as it will allow Antonio Conte and his players to get a good look at them for themselves before they meet again in the intimidating Juventus Stadium.
But Ledley remains confident they have a puncher's chance of landing a knockout blow if they can catch Juve off guard.
And he revealed they have a tried and trusted method of dealing with all the hype that surrounds such a high-profile game.
The midfielder who turns 26 next week explained: "We just try to ignore all that is said by people about this game.
"We don't do anything like store it away and try to use it as extra motivation.
"We prefer just to speak about it between ourselves, but we know it is still a long way away and that we have a lot of important games between now and then.
"When the Juventus game comes up, we will be ready.
"We are good professionals here and know how to deal with a situation like this."
The time lapse between qualifying from the group stage in early December, the draw for the last 16 a fortnight later, and the games actually kicking off in mid-February, lends itself to every available opinion being sought and published or broadcast.
If it was all that the Celtic players had to look forward to when the season resumes on Saturday with a home game against Hearts, that might be more of a problem.
But, as Ledley's calm demeanour illustrates, it is being handled with aplomb.
He does, however, reckon they people offering up opinions should think a bit more before they speak.
"I definitely believe we deserve to be shown more respect," he said, in a tone which indicated a nerve had been touched. "Even just the way we play football shows that.
"When I first came to the club, we played some fantastic football, but didn't get credit for that.
"Now the world can actually see what we are doing in the Champions League, including beating Barcelona.
"I don't think anyone outside the club gave us a chance when the group draw came out.
"We were told we were going to finish last of the four teams.
"But that's what we do, prove people wrong."
"We knew from when the draw was made that we had an opportunity," added Ledley.
"It was still a bit of shock when we beat Barca, because, for me, they are the greatest team in the world.
"But we thoroughly deserved it, the way we defended and hit on the counter-attack.
"The team unit is fantastic."
A fact which Ledley is delighted more and more people are recognising, even if the flip side is that it robs Celtic of their surprise element.
"We have shown what we can do, but it gives us a good confidence boost," he said.
"Opponents have to look at us and our game and they fear us knowing that we have beaten Barcelona and made it to the last 16 in the Champions League.
"It was one of those days you will always remember."