Grobler's ruthless pursuit of gold has helped make Great Britain the envy of the rowing world, and it's perhaps because he makes tough decisions look so easy.
Last year Great Britain were unbeaten in the men's four, winning the world title after a flawless and dominant season.
A few months later and that well-oiled crew has been ripped apart, Grobler putting all his aces in one pack for the forthcoming World Cup in Belgrade.
Andy Triggs Hodge and Peter Reed, who were part of the Olympic winning men's four in Beijing but have raced together as a pair for the last three years, will join Alex Gregory and either Tom James and Alex Partridge in the flagship of a powerful fleet.
Ric Egington and Matthew Langridge, members of last year's four, have moved to the eight and they will be joined by either James, an Olympic champion, or Partridge, a world champion.
Great Britain last won the Olympic eight gold in Sydney and will certainly consider this their best chance since, with the powerful crew also featuring Constantine Louloudis, an Oxford Boat Race winner who will stroke the boat and is 20 years younger than team-mate Greg Searle, who won Olympic coxed pair gold in Barcelona when his team-mate was just 11 months old.
"World Cups are important competitions in their own right but this one will be more significant than usual as it gives us the first glimpse of the potential 2012 racing form of our crews," said GB Rowing's performance director David Tanner.
"We are always ambitious to do well and will want to see a number of crews on the Belgrade podium.
"We will take into account performances in Belgrade as we shape the team for the remainder of the season."
Triggs Hodge and Reed may privately express disappointment that their adventure in the pair is over - they've won silver medals at the last three World Championships but in nearly 20 head-to-head races have been unable to best crack Kiwis Hamish Bond and Eric Murray, who will travel to London among the Games biggest odds-on favourites.
"If we can stay injury-free then I will be damned if anyone will beat us or come close," said Triggs Hodge, when asked about his return to the four.
"We can be a formidable force, give us some time together in the boat and no problems with illness and injuries and we can really be astonishingly fast, we can be electric."
Great Britain finished top nation at last year's World Championships but just four of the 14 Olympic class crews are unchanged for the first of three World Cup regattas in Serbia.
Women's pair Helen Glover and Heather Stanning, world silver medallists last year, are back together while world champions Zac Purchase and Mark Hunter look set to defend their Olympic title in lightweight double scull.
World champion double scull Katherine Grainger and Anna Watkins will lead Britain's assault for a first-ever Olympic gold in women's rowing.
The duo have dominated their discipline in the last two years but Grainger, with three Olympic silvers in her collection, will know to take nothing for granted after seeing similar form count for nothing at previous Games.
Alan Campbell is the only other retained crew, continuing in the single scull where he hopes to upgrade his world bronze against the likes of New Zealand's Mahe Drysdale and Ondrej Synek, of the Czech Republic.
So far Great Britain has qualified for 13 of the 14 Olympic events, meaning the pressure will really be on Annabel Vernon and Rachel Gamble-Flint, in the women's single sculls.
The final qualifying regatta for London will be the second World Cup of the season in Lucerne and the importance of the next few weeks won't be lost on Vernon, a silver medallist in Beijing.