In his final outing for the Perth club, the veteran produced a masterclass in leading the line, claiming a hat-trick to sign off in style.
Manager Tommy Wright allowed him the exit he deserved, withdrawing him after 64 minutes so that he could receive a sustained standing ovation from the away fans. MacLean savoured the moment and this clever player had done enough to suggest there will be more goals to come from him in a maroon shirt.
“Players don’t stay at clubs if they don’t do their jobs but he’s given me everything,” said Wright. “He’s been a leader for me and I’ll miss him.
“The move to Hearts was just too good for him at his age to turn down. I wish him well.”
A quarter of an hour had passed before there was even a ripple of excitement. The hosts ought to have moved in front when Liam Grimshaw’s incisive pass released Curtis Main but the striker prevaricated and, by the time he finally pulled the trigger, Jason Kerr was able to block his effort.
It was to be one of the few occasions on which they threatened and, once Saints moved in front, the outcome was never in doubt.
MacLean began the rout with a firm downward header from Richard Foster’s cross and Steven Anderson fired home the second after goalkeeper Trevor Carson had parried a Murray Davidson header.
MacLean struck again before half-time, sliding in to force home Matty Willock’s low cross at the near post as Saints took full advantage of the home side’s defensive disarray.
Motherwell made changes at half-time but the pattern did not alter, although the contest might have become more interesting if substitute Nadir Ciftci had scored instead of volleying straight at Zander Clark from point-blank range. Any ifs and buts were dispelled when MacLean completed his treble, poking home a cross/shot from David Wotherspoon before taking his leave.
Gael Bigirimana then headed home after Ryan Bowman had struck the crossbar with a shot but not only was that response too little, too late but substitute David McMillan, who had replaced MacLean, added a fifth, diving full length to head home another sumptuous Foster cross.
Motherwell manager Stephen Robinson made no excuses for his side’s uncharacteristically atrocious display. “The consolation for me is that, in 36 games, I’ve never seen us defend as poorly as that,” he said. “We haven’t had 18 clean sheets this season defending like that.
“St Johnstone took their chances and Steven MacLean was excellent but we were punished for every mistake we made. The good news for me is that I know they can be rectified.”