Coming after their loss at Halifax nine days previously, this again demonstrated that they do not have the depth in their squad to defend their title successfully.
Under those circumstances, the last thing they needed yesterday was to meet a Castleford side smarting from last week's defeat by Gateshead and responding by lifting their game immeasurably.
Tackling superbly, making far fewer mistakes, and, when they got the chances, attacking far more incisively, they always looked destined for a rare win at Central Park, their first in Super League.
A clever kick from Danny Orr set them on their way, Brad Davis beginning his outstanding personal contribution by winning the race to claim a try improved by Orr.
An exchange of penalties kept that six-point lead intact before Castleford stunned Wigan with a second try on the half-hour.
Orr's pass sent Francis Maloney away and the ball took a deflection to lob neatly into the arms of Jon Wells.
Castleford showed no sign after the break of believing that they had done enough and attempting to sit on their lead. Instead, they stepped up the pressure with three sets of tackles near the Wigan sticks, before Davis' swift ball from dummy-half sent another of their heroes on the day, Adrian Vowles, over for the points that effectively took them out of reach.
It was 11 minutes from time before Wigan averted the ignominy of going tryless. Tony Smith, back in the side for the first time in almost three months, did not place his kick well, but Phil Jones, making his first start for the club, stole it from Wells for Mark Reber to touch down.
There was no real prospect of a late Wigan fightback and Castleford confirmed their clear superiority when two former Wigan players, Gael Tallec and Danny Ellison, took them upfield and Jason Flowers got his pass away for Lee Harland to score, Ian Tonks kicking the goal to add to Orr's three previous successes.
Long before that stage, Wigan's supporters were making their views known by jeering their side's mistakes, walking out, or both.
"We're doing it pretty tough at the moment," said the Wigan coach, John Monie. "And I don't have all the answers.
"We aren't playing well enough to beat sides in the top half of the competition."
Castleford's Stuart Raper joined his players for emotional celebrations on the pitch after the final hooter.
"It's one of the highlights of my career as a coach to beat Wigan at Central Park," he said. Just at the moment, that is not as difficult as once it was.
Wigan Warriors: Davies; Robinson, Moore, Connolly, Jones; Florimo, Smith; Cowie, Cassidy, Mestrov, Gilmour, Betts, Farrell. Substitutes used: Goldspink, O'Connor, Reber, Bretherton.
Castleford Tigers: Flowers; Wells, Eager, Maloney, Rogers; Orr, Davis; Sampson, Raper, Sykes, Fritz, Harland, Vowles. Substitutes used: Pickering, Tonks, Tallec, Ellison.
Referee: S Ganson (St Helens).Reuse content