Even then, the Auckland lefthander has been an in and out proposition there too.
Born in Durban, the 28-year-old made his first-class debut for Auckland in 2006-07, but it took some time for him to make an impact.
In November 2012, Munro belted 269 off 252 balls against Wellington at Eden Park's outer oval - 27 fours, 14 sixes - while sharing an Auckland sixth-wicket stand of 377 with Craig Cachopa.
Last March, he improved on that. Munro clouted 281 off only 167 balls against Central Districts in Napier, hitting a New Zealand record 23 sixes - seven more than the previous record.
He put on 214 in 26 overs with Robbie O'Donnell, an Auckland fourth wicket record against CD. His 100 took just 67 balls.
This season, Munro topped the aggregates in the T20 domestic competition, belting 366 runs in 10 innings at a strike rate of 175.96 to carry Auckland to the title.
Indeed his strike rates make compelling reading.
In 20 T20s he's going at 153.33; in 12 ODIs it is a slightly more pedestrian 94, with an average of 27.11. In first-class cricket Munro averages 48.2, at 93 strike rate, with nine hundreds. The point is, he scores fast no matter the format.
Among the keys to his recent success are not pre-planning.
"I've been trying to stay still and not pre-meditate too much, like I have in the past," Munro said.
He made 36 off 26 balls against Sri Lanka in the first T20 at Mt Maunganui, having to battle through a difficult early period with the boundaries wouldn't flow. He admitted that a couple of years ago he'd have struggled avoid throwing his wicket away.
Now, greater maturity and sense of self-belief that he can catch up if he has a sluggish start have helped.
Colin Munro's innings at Eden Park
0, 6, 2, 6, 0, 6, 6, 0, 6, 1, 6, 1, 4, 6
"I'm trying to back my offside game. In the past couple of years I've been looking legside," he said.
"I have been working on it with (Auckland coach) Mark O'Donnell, trying to hold my shape and hit through the offside.
"Then if they do come straight at me, my natural thing is to hit over cow (corner) and square leg."
In both T20s against Sri Lanka, he spent time in the middle with captain Kane Williamson, and it's never a bad thing to produce strong form with the skipper looking on at close range.
Opener Martin Guptill held the New Zealand record for fastest T20 50 at 19 balls, for about 10 minutes yesterday. Then Munro blew that effort out of the water.
''I'm not sure what these two had for breakfast but it was unbelievable to watch,'' Williamson said.
''Guppy been doing it all summer and to see Munners helped was pretty special. It was world class hitting which we'll only continue to encourage these boys to keep going.''
Munro, who had no idea how close he was to Yuvraj's record, was chuffed.
"I've shown glimpses in the Georgie Pie (domestic competition) what I can do and it's just pleasing to do it on the international stage," Munro said.
He had put up a case for selection which the national panel simply could not ignore.
"His statistics are so compelling we just didn't feel we could leave him out," national selector Gavin Larsen said when Munro was confirmed in the T20 squad.
"His numbers speak for themselves, he's had a couple of fantastic seasons at domestic level and he has seriously shot the lights out."
As he did so spectacularly yesterday.
Munro has all but assured himself of a trip to the world T20 tournament in India in March.
New Zealand had a problem hole to fill in the top three, with the retirement of Brendon McCullum. It looks they've found their man.
