Blues v Waratahs
Kickoff: 9:35pm Saturday, 16 March
Allianz Stadium, Sydney
The Blues have reverted to a standard bench make-up for this weekend after their 6-2 split badly backfired against the Hurricanes.
Failed HIA's for Zarn Sullivan and AJ Lam left the Blues with a halfback on the wing for majority of the game.
Cotter said in hindsight, it was a mistake to go with one less back on the bench.
"I have to say yeah, I got it wrong. But I didn't know that when we made those decisions. It seems to be now with smart mouthguards and head knocks that we might have to rethink a little bit how things can unfold."
However, he would not rule out revisiting the tactic in the future.
"I think there's conditions and teams that you play against where you feel you can take an ascendancy in the tight."
The Blues have returned to a standard bench for their clash with the Waratahs in Sydney on Saturday night, with Sam Nock, Harry Plummer and Cole Forbes the three back reserves.
Cotter said the Waratahs looked dangerous in their win over the Crusaders and close loss last weekend to the Highlanders.
"They're up. You can see that in their energy and the way they're playing. They're hard to play against because they apply a lot of pressure and play off your errors so it's been a big focus for us to be as accurate as we can."
He said the error count against the Canes was far too high, having conceded possession 18 times.
"We really want to tidy that up because we created opportunities but didn't get over the line. Sometimes you've got to be a bit tough on yourself. It's an individual thing around how we go about our business and you can't knock off too early."
Despite the loss in Wellington, it's far from panic stations for the fifth placed Blues.
"If it was the end of the season, you'd be worried but it's the beginning of the season, we learned quite a bit about ourselves and our preparation and execution and how you have to adapt."
Cotter said results over the opening three rounds have reinforced how tight the competition is this year.
However, he was not writing off the defending champions following their 0-3 start to the season.
"The Crusaders are still the Crusaders, they can turn it around at any time, and we feel they haven't been playing badly. It's just the rugby ball bounces in odd ways and just the way it is and I think this competition this year is going to be about that sort of thing and just rocking through the tough times."
The Crusaders will take on the Blues at Eden Park next weekend in the second of three Kiwi derbies on the trot.
"It's a tough game for them this weekend and we've got them in two weeks time. So it's relentless but I think it's exciting. I think it's a good thing, it just keeps everyone on their toes."
Saturday will also mark the return of Hoskins Sotutu, Caleb Clarke and Ofa Tu'ungafasi from mandatory All Blacks rest.
Blues: 15 Zarn Sullivan, 14 Mark Tele'a, 13 Rieko Ioane, 12 Bryce Heem, 11 Caleb Clarke, 10 Stephen Perofeta, 9 Finlay Christie, 8 Hoskins Sotutu, 7 Dalton Papali'i (c), 6 Akira Ioane, 5 Laghlan McWhannell, 4 Josh Beehre, 3 Marcel Renata, 2 Kurt Eklund, 1 Ofa Tu'ungafasi
Bench: 16 Soane Vikena, 17 Joshua Fusitu'a, 18 Angus Ta'avao, 19 Cameron Suafoa, 20 Anton Segner, 21 Sam Nock, 22 Harry Plummer, 23 Cole Forbes