The New Zealander, who saw his side receive a 50-point hammering in Johannesburg back in August, believes Peter de Villiers' men are currently the team to beat, despite a slow start to the last calendar year.
"They obviously won the World Cup (in 2007) and, you look at last year, their performances were a bit flat post-World Cup," said Deans.
"But you look at the performances across the year and the best performance was what they did to England at Twickenham, and what they did to us at Ellis Park."
Although the Boks finished bottom of the Tri Nations table, they finished their campaign by thrashing Australia 53-8 in their final match and then brought the year to a close on a massive high thanks to a stunning 42-6 win over England.
Having seen the world champions at first-hand, Deans believes the nature of those performances alone should lead the South Africans to be regarded as the most dangerous team in international rugby.
"They were the stand-out performances in the calendar year," added Deans.
"Sure the All Blacks retained the Bledisloe Cup and walked away with the Tri-Nations but in terms of compelling performances they belonged to South Africa."