Once one of the most promising bowlers in the country before problems befell him with his action, yesterday was the latest evidence that 25-year-old Calum has completed a characterful transformation into specialist batsman as he blasted the Netherlands bowling attack to all parts of Glasgow's south side.
His 145 out of Scotland's 317 set up a convincing win - by 144 runs under the Duckworth/Lewis system after the Dutch had been reduced to 115 for seven before rain forced an abandonment - as they responded to Tuesday's sloppy defeat to the same opponents in emphatic fashion.
However, the nature of his passage through the 90s - rather more deliberate than the way he reached his half century with a stunning back foot off drive into the pavilion for six - also meant a fretful half-hour or so for mum just as she was readying herself for another important appointment.
Matters were made no easier for her by the rather more relaxed approach adopted by husband Donald, Cricket Scotland's official photographer, as she sought to alert him to the need to head as quickly as possible to West of Scotland University to see youngest son Neil graduate with honours in sports development.
"I don't blame them [for wanting to get away]," MacLeod said with a smile at the end of the game.
"You only graduate once so it was a big day for Neil as well. I'm just happy that I was able to score some runs and give them some problems. It's the first hundred that especially my mum had managed to see so it's a proud moment for me."
That saunter through the 90s apart, it was a wonderful effort, though he survived a scare when he got the benefit of a close call with a run out shout when on 10.
"It felt tight, but the umpires are there to make a decision," MacLeod observed, pragmatically. "That's the luck you need sometimes to get you going. After that I played a little bit more freely and the way I'd like to."
His mother apart he surely impressed the onlooker he most wanted to after Grant Bradburn, Scotland's new head coach, had challenged the batsmen in particular to improve on Tuesday's showing.
"We threw it away twice," MacLeod acknowledged. "Some of the batters had to have a look at ourselves. Grant was quite open and told us that and thankfully I managed to get through that and I'm sure on another day it will be one of the other lads as well."
Perhaps so, but this was MacLeod's match as he dominated an innings to which Preston Mommsen also contributed well with his second 45 in consecutive days, while Josh Davey also helped maintain the momentum with a brisk 34 in partnerships of 92 and 84 respectively.
On an overcast morning they had lost the toss for a second time, but the very different weather conditions and the presence of a bit more of a covering of grass on the wicket this time persuaded the Dutch to field, making it a good toss to lose since it let the Scots do what instinct was telling them to without having the responsibility for the decision.
That there was more than enough in the wicket for the bowlers was, however, highlighted when the Dutch batted and the first wicket fell immediately after a delighted Gavin Main, the Durham teenager who had been called into the side to replace the injured Ali Evans, was introduced into the attack.
Having hit the previous four balls from Safyan Shariff for 19 runs, Stephan Myburgh was looking to sustain the assault as he went to pull the Durham quickie's first ball, only to nick it to wicketkeeper Marc Petrie, the other man called up for yesterday's game.
He could have had two more had two more catches not been negated by 'no ball' calls which is a problem that must be addressed quickly. However Michael Leask, who had failed with the bat but is rapidly turning into one of those players who simply cannot be kept out of the game, then took the initiative with four wickets for 19 to leave the visitors in disarray when the rains came.