An in-depth report of this match will be sent to Ian Murray this week to help his Dumbarton side prepare for a trip to Pittodrie on William Hill Scottish Cup duty.
The manager might have already been given the gist: Aberdeen have a penchant for going off-message after the interval.
What had been a performance full of first-half fizz became one as flat as a glass of cheap Cava that has been left sitting out for too long. Ryan Jack's early goal had heightened expectancy among the home support, many of whom had seen their side crush St Johnstone in a Scottish League Cup semi-final at Tynecastle just a few weeks ago. There was a sense that the Pittodrie side might emulate that 4-0 cup win in the SPFL Premiership on Saturday, only for the performance to dip after the break.
There was a lack of cohesion to what Aberdeen did, too little concentration and the zip with which they had dominated the first half also dissipated. Alan Tate, competent and cool at centre-back as club captain Russell Anderson was left on the bench for the second successive game, looked back on a similar pattern in the midweek victory over Celtic but failed to explain such a collapse.
"I don't know why that should be but St Johnstone put a lot of pressure on as they need points to clinch a top-six finish," he said. "There are financial implications if they don't make it, so there is a lot for everyone to play for as we are going for second.
"If we do finish as runners-up in the league then you look back to games like these and realise it played a big part in the achievement. There are times when things don't seem to be going well for you at this stage of the season as points get harder to come by. But it shows the sort of mentality you need to be successful if you can overcome that and beat teams."
A similar resolve was required of Jack, with the midfielder making his return from a hip injury on Saturday. It was the first time that the Scotland Under-21 internationalist had played for the first team since January 25 and brought his first goal of the season, with his manager extolling his efforts in returning to fitness earlier than first anticipated.
"He'd done bits and pieces of training in the past few weeks. We trained on Friday and he was the best man on the park," said Derek McInnes. "We felt his freshness would be a good opportunity to get him 60 minutes under his belt and the goal is his just rewards for his comeback.
"We're mindful we have got important games coming up. Ahead of the [League Cup final against Inverness Caledonian Thistle on March 16], we took the opportunity to get Ryan back into the squad a bit quicker than we would have thought, but that's down to him and his attitude.
"It was down to his behaviour on the training park, he's healthy enough to take part. He's worked hard with the medical staff, and Ryan coming back into the team with the two cup ties ahead of us might just give us a jag at the right time."
St Johnstone waited too long to improve at Pittodrie. Shots from Lee Croft and Michael O'Halloran came close to levelling the score but there was a sense of frustration within the side; Steven MacLean's red card following a needless late foul on Aberdeen's Nicky Low, upsetting his manager, Tommy Wright.
The incident came too late to affect the outcome of the match and it was the loss of the goal which rankled with Alan Mannus most. The St Johnstone goalkeeper later explained why he had failed to make what appeared initially to be a relatively simple save.
"I couldn't see the ball and I leaned to my left to try to see it," said Mannus, whose side are three points ahead of seventh-placed Inverness Caledonian Thistle. "As I have done that he has fired it to my right and as I changed direction I slipped. I tried to push off and my foot gave way. I would have saved it comfortably if I hadn't slipped; so that is a big frustration."