They returned to the top of the table with a win which was also their finest Super League result against Wigan, eclipsing the 42-14 success two years ago.
However, Powell also felt it was a superior performance to the one that saw his dynamic side vanquish Leeds Rhinos 66-10 at Wheldon Road earlier this term.
“Leeds were missing a lot of players that night,” he said.
“Wigan had as well but they’ve got a deep squad and the players they had out there were high quality so for us to be as good as we were is pleasing.
“I didn’t expect us to get away from Wigan like that. We started the game so positively and defensively we were on the money so I’m delighted with the way the players went about their work.
“They were superb from start to finish. It was tough for them losing a couple of blokes and, when they were down to 12, we hit them pretty hard and executed pretty well.”
Castleford lost stand-off Benny Roberts to an injury that, though not “serious”, will keep him out of Thursday’s game at Huddersfield.
Wigan saw Anthony Gelling (knee) depart early on and later Taulima Tautai (neck) and Ryan Sutton (ankle) while Ben Flower suffered a suspected snapped Achilles towards the end.
England stand-off George Williams failed to return for the second period, too, with a knee injury that saw him ruled out of Saturday’s Test against Samoa, Warrington Wolves’ Kevin Brown flying out to Sydney instead.
But Wigan coach said Shaun Wane insisted: “It’s not acceptable. They were too good for us.
“There are no excuses from us about personnel, Wigan teams don’t get pumped like that at Castleford. The players are hurting. We got absolutely schooled.”