Cardiff have plenty of firepower in the backs but need to provide a platform if they are to make the next step.
The Blue and Blacks qualified for the play-offs last season by finishing sixth but were comprehensively beaten by Stormers in the quarter-finals.
“It is obvious, our set-piece needs to improve,” said flanker Dan Thomas in the immediate aftermath of the Cape Town loss.
“The Stormers were dominant and we didn’t cope. We knew it was coming and still couldn’t stop it.”
Loose-head prop Scott Sio, who won 74 caps for Australia, arrives from Exeter charged with helping to drive improvement in that department.
“One of the biggest things Cardiff want to pride themselves on is that set-piece,” said the 34-year-old.
“Hopefully I can be a good cog in the wheel there and provide some experience.”
Sio made the last of his 86 appearances for Chiefs in June’s Prem final at Twickenham and still harbours ambitions of reaching a third World Cup, now with Samoa.
“He is very experienced and wants to look after the boys around him in the changing room, in the gym, on the pitch,” said head coach Corniel van Zyl.