For example, the Bulls beat the Stormers 40-3 in the first round of the season while the Lions — finalists in 2016 and 2017 — beat the Jaguares 25-16 in Buenos Aires.
A week later, the Stormers beat the Lions in Cape Town, while the Bulls lost to the Jaguares in Argentina.
In week three, the Stormers beat the Sharks and the Bulls beat the Lions in away matches, dismissing to some degree the influence of home advantage on the changes in fortune.
The Bulls then beat the Sharks twice, 37-14 in Pretoria in round five and 19-16 in Durban in round seven before the Sharks achieved an improbable 37-point win over the Lions in the round just ended.
Form fluctuations can be explained by injuries, the imperative in World Cup seasons to rest top players, home advantage and even the weather. But even Lions coach Swys de Bruin was at a loss to explain how his team, which has risen so high in recent seasons, fell so low against the Sharks.
"I'm very disappointed," said de Bruin, who signed a two-year contract extension the week before the match. "It was the same against the Bulls. Physically, they had us from the word go.
"It is a thing we have to get right. We were not up to it. We were never, never in this game. Why? I don't know. I'll start with myself and see what we did wrong. They were just all over us physically, especially at the ruck."
The Lions now face a tough tour to New Zealand and Australia in which they will play the Brumbies, Chiefs and defending champion Crusaders.
Wins may be hard to come by; in the first venture by a South African team to Australasia this season, the Stormers lost to the Hurricanes, Blues and Reds.
De Bruin is more interested in seeing his players demonstrate more character than they did against the Sharks.
"I'm here for effort, character and guts and I didn't see that. It is a real concern."
The Jaguares also pulled off a major upset in round eight, beating the Bulls 22-20 in Pretoria, although that was a result in part of the Bulls being reduced by yellow cards to 13 players in the second half.
Pumas first-five Domingo Miotti, who made his debut off the bench, scored two tries while the Bulls were undermanned to lead the Jaguares to a win which bounced them off the bottom of the South Africa conference.
Bulls coach Pote Human had no difficulty in putting his finger on the cause of his team's defeat.
"You can't play a team like that with 14 guys and then 13 at the end," he said. "It was just ridiculous. The stupidity of the players. I really thought we had them and we let it slip."
- AP