Outgoing Reds boss Ewen believes the Crusaders are heading in the right direction and will be a threat during the rest of the tournament.
This after his side suffered a humiliating 38-9 defeat to the seven-time champions in Christchurch on Saturday.
"You have to be there and you have to be right for the night but we didn't get it right," said McKenzie who will now leave the Reds to take charge of the Wallabies.
"They defended well, they certainly attacked well, their breakdown work - all those things are important come finals time.
"They know that. Their form-line coming into this game was pretty good and I've been really impressed with their efforts over the last three weeks so that's what you need.
"You need to be playing well at the right time, and they certainly are."
McKenzie feels his side's slow start proved their undoing.
"They went through, scored two tries and they you are under pressure chasing and it's not a great place to be in," he added.
"We've been really proud of our defence all year so it was a disappointing night for us.
"It's the worst night in terms of leaking tries for the whole season. We're a better team that we showed tonight," he said.
Meanwhile, Reds captain James Horwill said the Crusaders were clinical and had made the most of the Reds' mistakes.
"If they continue to play like that they will be a tough team to beat in this competition," he said.