But Robertson's Crusaders found a way to keep them tryless over 80 minutes, by simply ruling the set pieces through their all-international tight five.
"They got the job done," Robertson told Newstalk ZB's Tony Veitch. "They got a couple of really good drives going at key times and, obviously, some dominant scrums.
"When you've got an All Black front row, you need to use them well and the back row also. Then you get a guy like Quentin Strange come on [at lock], three games in, and you wouldn't even know ... that makes you just as proud."
Over week shortened by travel home from their South African road trip, Robertson and his staff were also able to defuse perhaps the most potent backline in Super Rugby, anchored by the brilliant Barrett brothers.
Somehow, he has steered this side to a flawless record, despite a long list of injuries and suspensions that saw him without the services of Kieran Read, Sam Whitelock and Israel Dagg last night ... and then losing acting skipper Matt Todd and Scott Barrett along the way.
Unheralded players like David Havili, George Bridge, Pete Samu, Whetu Douglas and Strange have stepped seamlessly into the void, showing a depth and team culture that has been a trademark of the Crusaders over their history.
"I know my footy," Robertson told Veitch. "I know how I want to play it and how I want to structure my week.
"I've been mentored pretty well by Rob Penney - I spent five years behind him with Canterbury , learning a way he did it - and I've been coached by a lot of great coaches over my time and found my way.
"Now, for my players, I want them to come in and be really clear, go out and play a simple game plan, and express themselves.
"I want them to have fun on Mondays, give me what I need from them and then give it all on a Saturday, which is what they're doing."
Despite seven Super Rugby crowns, the Christchurch-based franchise has not tasted that glory since 2008, enduring eight years of "close, but no cigar" since. Over that time, with some of the game's biggest stars at his disposal, Blackadder took the Crusaders to two finals and four other semi-finals, without quite reaching the pinnacle.
But if Crusaders faithful expected a rebuilding season as their new coach found his feet, they will have been pleasantly surprised with progress so far.
"My proudest thing is that the boys really care and they show that on the field," said Robertson, 42, who played 23 tests at openside flanker for the All Blacks from 1998-2002.
"One of our goals as a team was to fill our stadium, not just in the finals, but during the round robin. We did that, because everyone knows we're playing for each other and they want to be part of it.
"I don't want to get carried away, because everyone remembers the last game and that's the one we've really got to win ... that's what we're preparing for.
"I don't know if it was a surprise, me getting this job, but maybe it's not now."
Having just returned from South Africa, the Crusaders now face quite a different challenge, as they head to Fiji for their next outing against the Chiefs, now the next best New Zealand side on the competition ladder.
With a big Fijian contingent on his roster, Robertson is well aware of the distractions on offer at this very important juncture of the season.
"With the conferences and the way they're structured, you've just got to win these games, if you want to play at home in front of your people at the end of the year," he said.
"We know how critical it is to do that, otherwise the challenge becomes enormous. We've given ourselves a bit of a buffer [over the Chiefs], but this Friday is critical to us to continue our momentum.
"Our forward pack has got to play the Lions too, so they continue all the way through and the more buffer we can get, the better for us at the end of the season."
