South Africa's conditioning coach Neels Liebel said on Monday he had facts to show northern hemisphere rugby was slower than the game played in the southern hemisphere.
Liebel told a news conference the new global positioning system (GPS) the Springboks are using to track the movement of players during games and training had proved those based in Europe were behind the pace of locally-based internationals.
De Villiers has fielded five European-based players this season - props CJ van der Linde (Leinster) and BJ Botha (Ulster), number eight Joe van Niekerk (Toulon), fullback Francois Steyn (Racing Metro) and flyhalf Butch James (Bath).
‘This GPS system allows us to do very close monitoring of the players, the distance they run, the pace they are running, and for guys like BJ and CJ, their clubs are also on the system and they have sent us all their data,’ Liebel said.
‘From all this we have seen the players from overseas are playing at about half the intensity of the Super 14 in terms of the speed they play at. It's a slower game there and players from there struggle to keep up with the pace.’
Van der Linde and James are in the squad to face New Zealand in the Tri-Nations in Johannesburg on Saturday.
‘It's taken four or five weeks for us to get those (European-based) players to the intensity we wanted. Before that they were not getting to the ball quickly enough,’ added Liebel.
‘There's nothing wrong with their conditioning, it's just the game is different in the northern hemisphere, they play closer to the rucks, they don't often move the ball further than five or six metres from the ruck.’
Liebel also defended Springbok captain John Smit, who is due to win his 100th cap on Saturday but has been under-fire over his form and fitness.
‘John is in a good physical condition, the distance he's been running and the pace he's been running are up there with his usual stats,’ said Liebel.
‘His weight is the same as it has been the last two or three years and with the exact same fat percentage. So I have no concerns about his fitness at all.’