Seven goals was the least Celtic deserved. In truth, had they scored 14 then Motherwell could scarcely have raised an objection.
If there was any doubt as to what kind of performance Celtic could find on Deila’s last day then it was answered early and emphatically.
Even before they opened the scoring midway through the first half, they created a long series of decent chances.
Rogic went close on three different occasions, Christie had two opportunities and Lustig one.
From the get-go, Celtic had a dynamism about them that Motherwell couldn’t even get close to living with.
Sure, it was a match with nothing at stake, but there was a tempo and an accuracy about their game that was exhilarating.
In the absence of midfielders Scott Brown and Nir Bitton, they had the brake off and they were relentless.
The rout was started by Tierney, a fitting flourish in a terrific breakthrough season for the teenage left-back. He cut in from the left and beat Conor Ripley at his near post.
Five minutes later, Rogic made it two and this one had a lot to do with the excellent Armstrong, who, after playing a one-two with Christie, hit a post with his shot. Rogic was on hand to tap in the loose ball.
The home fans had barely retaken their seats when it was three. An Armstrong corner was missed by the flapping Ripley and was headed home at the back post by Lustig.
Motherwell knew what was coming next – waves and waves of green and white. When they had the ball, they couldn’t keep it. When they didn’t have it, they didn’t have a clue how to get it.
They were utterly bamboozled by Celtic’s energy and should have been four behind before the break when Ripley tipped a Rogic shot into Christie’s air-space. The former Inverness Caledonian Thistle youngster had to score but put it over, much to his embarrassment.
Not that it mattered because Celtic continued the deconstruction just after the break, Armstrong teeing himself up with a nice first touch and an even nicer second one, a delicious hit into Ripley’s top corner.
Celtic Park lapped up this ruthless version of a team they have seen toil too often this season – a fast-moving, creative force that refused to ease Motherwell’s torture.
The visitors were like sitting ducks. This was a feeble and mortifying end to their season.
The fifth came quickly, Armstrong’s good work starting it and Roberts’ curling finish ending it. Motherwell backed off him and duly got what they deserved.
Four minutes later, the sixth arrived, Rogic playing Christie through and this time he made no mistake, drilling his shot past the hopelessly isolated, and totally befuddled, Ripley.
The great feel-good goal was the last one, though. Aitchison, born in 2000, slammed home his first shot on goal in senior football, a strike that will live forever in his memory no matter how many he goes on to score at this level.
For Deila, it was the perfect send-off. As the supporters of his soon-to-be former club celebrated the title into the night, the manager would be on a flight out of Glasgow, back to Norway, back to the life he had before he entered the mad world of Scottish football.
After this rout, he would have left with a smile. A bittersweet one for sure.