Wellens led from the front with some brilliantly crafted tries, showing his skills as a support player, as a power player and also a clever player. The pick of his four coming in the second half, when he darted over from 5 yards after fooling four Wigan defenders.
The early exchanges were tight, Francis Meli and Bryan Fletcher exchanging tries for a tied game.
But two tries from Wellens, sandwiched by a Matt Gidley effort, saw Saints stretch away in a flash, putting them 22-6 in front.
And the game was essentially over just five minutes in to the second half when Wellens crossed for his hat trick. Wigan grabbed consolation tries through Union bound Chris Ashton and Darrell Goulding, sandwiched by a fourth for Wellens which led Saints to a 34-18 win over their arch rivals.