Plummer missed an earlier conversion too, but his high-profile opposite Richie Mo'unga had a shocking night with the boot as well, and besides, the Blues had other chances to get across the line.
One of the big problems with the Blues last year was a lack of workrate – especially when choosing whether or not to chase back on defence to tackle or support an under-pressure teammate. When the lungs are burning it's easy to take shortcuts but champion players and teams don't and statistically the Crusaders were among the best in this area.
There were few signs of that at Eden Park and the Crusaders had to dig far deeper than they had perhaps expected in order to get the job done. In the final, frantic, minutes they looked rattled in the extreme and it was desperation and a bit of luck which got them home.
"It's frustrating, obviously, not to get the result we were looking for," MacDonald said afterwards. "It was just a good game – it ebbed and flowed, the momentum, from both teams.
"A couple of calls probably didn't help us and there were a couple of plays that we didn't execute. It will be frustrating to look at the video, but on the flipside of that there were parts of the game in which we were very good and put on a lot of pressure against a very good team. If we can do that for longer periods of time we will be hard to stop."
The backline needs a bit of refining, but the Blues' pack appears to have the power and grit to trouble every team in the competition.
All Blacks tight forwards Karl Tu'inukuafe and Ofa Tuungafasi and Patrick Tuipulotu, plus the likes of Akira Ioane and newcomer Tom Robinson are all extremely large and good at what they do. The Blues scrum hurt the Crusaders' at times, although they did concede the second of their two penalty tries here.
Ioane, celebrating his 50th game for the Blues, was a man possessed with the ball and Northlander Robinson, 24, possesses just the sort of mongrel that this team needs.
"That's a good pack – that Crusaders pack has carried that team to two titles in two years and they showed that tonight," MacDonald said. "They were put under pressure at scrum time and then they responded – that's why they're the defending champions. There's a lot for us to take away from that as well."
MacDonald wanted two wins from the first three games, which means the Blues will have to beat the Sharks at Kings Park and Jaguares in Buenos Aires. At this rate they will be favourites to do so.