The Iron captain was part of the Bradford City side who suffered heartache in both the 2016 and 2017 League One promotion deciders.
Millwall proved to be the Bantams’ nemesis, triumphing 1-0 in last season’s final at Wembley after also having got the better of the Yorkshire club in the previous year’s semi-finals.
The memories of that loss under the Arch 12 months ago remain particularly vivid for McArdle.
“If there is anything I can learn from the last two years in the play-offs with Bradford it is probably the experience of what it was like to lose at Wembley last year,” the 31-year-old Sheffield-born defender reflected to The Yorkshire Post.
“Getting so close to promotion makes losing even worse. It was such a late goal and there was so little in the game.
“Sitting there on the pitch after the final whistle was horrible. It is a long enough season as it is, so to extend that by two or three more weeks you need to win to make it worthwhile.
“Watching Millwall celebrate was difficult, it was obvious what winning the final meant. We had wanted to be in their place and yet all we could do was watch.
“Looking around at our fans and all the disappointment there was in the stand showed what promotion would have meant to them.
“They were devastated and the feeling is probably one of the worst in football.
“I don’t want to experience it again. I will pass on to the lads just what a horrible feeling it was and why we can’t go through that this time.”
Scunthorpe finished the regular season in fifth place, five points behind the Millers.
The two tussles between today’s combatants also went the way of Rotherham, who followed up October’s 2-0 home win with a 2-1 triumph at Glanford Park four months later.
“Rotherham are a good team,” continued McArdle.
“I know they had a bit of a wobble at one stage during the run-up to Christmas, but they have been up there pretty much all season long.
“They went on a long winning run and there has been no real let-up since. That shows the consistency levels are there and that Rotherham know how to win games of football.
“In the two games we played them things were tight overall. Both teams had chances and I would imagine both teams fancy their chances.
“We will go into it like the last six games, treat it as a normal game and look to do our jobs.”
McArdle’s capture by Scunthorpe last summer on a free transfer was something of a coup.
He had been a stalwart of the Bantams’ defence for five years, during which he had helped the club to promotion and the League Cup final.
There can be little doubt that Bradford have missed McArdle, who admits to being surprised that his former club’s season fell away so dramatically in the new year.
“Bradford remind me a little of ourselves,” added the defender, about to compete in his fifth play-offs after helping City to promotion in 2013 and reaching the League Two final with Rochdale five years earlier.
“They had a bad run, but, where we bounced back, it didn’t really happen for Bradford. In a way that helped us because there were a few teams like Bradford who couldn’t buy a win.
“No one really got away from us as a result. We came through it and, thankfully, got our form back.
“When the fixtures came out last summer I saw we had Bradford last on the list and I really did expect it to be something of a decider on the last day.
“That looked even more likely in January and into February. Thankfully for us we got the win on Tuesday (against Plymouth Argyle) and that took the edge off it.
“I am sure the Bradford fans are disappointed after the last four or five years of progress, but I am also sure the club will learn from it and kick on again next year.”