This was only the Irishman’s third start of the season but he made the most of it with his fourth hat-trick for the club, taking his overall tally to an impressive 81 goals in just 163 appearances since Oldham Athletic astonishingly allowed him to leave for nothing.
That made it all the more inexplicable that the St Johnstone defence should seemingly forget just how dangerous Rooney could be by leaving him virtually unmarked at two set pieces in the first 18 minutes with predictable consequences.
To add insult to injury on a day when Tommy Wright described their performance as the worst in his time as St Johnstone manager, it was the Perth club’s former talisman May who swept in the cross that allowed Rooney a free header for the first.
The second was a well-worked corner kick routine involving May, Ryan Christie, a glancing header on by Anthony O’Connor and another Rooney header from close range as the opposition played at statues.
Not the sort of form you expect from them at a ground where they hadn’t lost in their previous five league visits and the rash tackle substitute Denny Johnstone made on Christie to allow Rooney to complete his hat-trick ten minutes from the end summed up a miserable day for Wright.
“There’s a lot of words I could use to describe that performance” he sighed. “It’s probably the worst 45 minutes I’ve had in nearly 200 games here.
“When players don’t pass the ball, when they don’t work hard for each other, when they give a quality side time on the ball, that’s what happens. You get gubbed, and we got gubbed.”
A fine save from Alan Mannus to deny Christie a goal and the post which kept out substitute Frank Ross’s shot late on prevented that from being more emphatically reflected in the scoreline.
It was still enough to take Aberdeen back level on points with Celtic at the top of the table, with a visit to Easter Road and a visit from the champions to come after the international break.
They are also six points clear of Rangers and St Johnstone below them now and Rooney warned that both himself and the Dons team have not yet hit top form.
“The gaffer said to us after the game that we haven’t really kicked into top gear yet,” he said. “We’re unbeaten and joint top of the league, so considering the lads are still gelling and we’re still finding our system, it has been a great start.
“We’ll go into the international break now ready for a few days off but the lads will come back ready to go again.”
Andrew Considine should be ready to go again for the game against Hibs as he missed this one with a broken wrist and Greg Tansey is expected to be fit to face Celtic after recovering from a hernia operation.
Of course Rooney is going to take some shifting but he was happy to head home with the man of the match champagne – and the match ball for his young son to play with.