On the back of the 23-23 draw with the Western Force last weekend, Deans said in his column on the Crusaders website that complacency had not been an issue until last weekend.
"Consciously I don't think it was an issue last week but subconsciously there must have been an element of complacency in our build-up.
"The 23-all draw has given us a huge shake-up and the guys are looking forward to getting a chance to play again.
"The Stormers might be 11th on the Super 14 table but we only need to look back to last week to see why we can't take anyone lightly," he said.
However, he has caused a surprise for South Africans by resting fullback Leon MacDonald, first five-eighths Dan Carter and flanker and captain Richie McCaw.
But he said they needed the break, and with the semi-finals in a fortnight it was timely.
The Crusaders are likely to be facing a Stormers side that has been caught up with internal turmoil. Things have been bad enough for a media ban to be imposed on the team's training this week.
It all stems back to the dropping of captain De Wet Barry after the Blues game in which he was sin-binned for a careless tackle.
Senior players in the team confronted management about Barry's axing and he was reinstated both as a player and captain.
Most recently, Springbok Jean de Villiers complained about being shifted out from centre to the wing for Saturday's game.
"It feels like being dropped and I'll have to talk to the coach," de Villiers told the Cape Argus.
"If I perform well at wing it could mean I will be playing there in the Springbok side," he said.
De Villiers has always expressed a preference for playing at second five-eighths.
Meanwhile, lock Ross Skeate, who has been one of the most consistent players among the South Africans this season, is looking forward to the prospect of going head-to-head with All Blacks star Chris Jack.
"I have been looking forward to this game for a long time," he said.