Reds playmakers Will Genia and Quade Cooper, in particular, are increasingly dominating matches.
The Brumbies, who maintained the competition lead, despite the slip at Suncorp Stadium, and the Waratahs are also looking ominous.
Former All Black wing Kirwan is sure the prize of being selected for the Wallabies to play in the three-test series against the Lions in June and July is a big factor in the form of Australian players.
"It's a bit like the World Cup, isn't it? In World Cup year everyone has an edge and wants to be selected.
"I know when I was playing, playing the Lions was a highlight. I just wish [coach] Robbie [Deans] hadn't left Quade out of his squad. Since he's been left out of thesquad he's been playing the house down."
Kirwan said the Australian players were showing excellent intent and technique at the breakdown - which is where the Chiefs faltered badly in losing to the Reds and Waratahs on successive weekends.
There was one other area in which they had an advantage - a proper pre-season.
"I think they've had a lot of time in the saddle pre-season, they had eight or nine weeks together which is a luxury we don't get. They are well drilled ... and there is that Lions jersey there so everyone's up trying to be selected and it seems to be that Robbie is looking at everyone, so that is the combination."
Kirwan, who has dropped in-form midfielder Francis Saili from his starting XV after an alleged driving offence, said skipper Ali Williams was managing a knee injury well and confirmed hooker Keven Mealamu would continue his bench role behind James Parsons for the match at Suncorp Stadium.
Asked to comment on the form of blindside flanker Steven Luatua, Kirwan said it was exciting and doubly so because of his background as a lock.
"We've been challenging him. He's been playing well on attack and what we wanted from him in the last game was a combination - an attack and defence performance.
"And he's learning and doing it really well. You have to realise he's come off a lot of locking. He's just improving week after week."