Deprived of 13 players by injuries, the reigning world champions survived a late Irish onslaught to get their four-Test season-end tour off to a winning start on Saturday after losing five of six Tri-Nations outings.
Skinstad, who retired in 2007 after an 11-year Test career as a loose forward, said Belfast-based Pienaar played a crucial role with his kicking game.
Largely ignoring calls for a ball-in-hand approach favoured by form teams New Zealand and Australia, Pienaar kicked for position and it worked well for most of the game with the home team struggling at the line-out.
"Pienaar gets my man of the match award. His kicking game was outstanding and he adapted well to the conditions," analyst Skinstad told pay channel SuperSport after South Africa ended a run of losses in Dublin.
Another former Springbok, right wing Ashwin Willemse, backed Skinstad and added that the entire South Africa pack, led by stand-in skipper Victor Matfield, was a close second behind Pienaar.
South African rugby writer of the year and long-time Springbok critic Gavin Rich took issue with the timing of some second-half substitutions by under-fire coach Peter de Villiers.
"It was a big call to take Morné Steyn off when he was kicking the goals that were keeping the Springboks ahead and when Adrian Jacobs came on, suddenly the backline looked disrupted," wrote the SuperSport blogger.
"This match may not be remembered as their most glamorous performance, but if it brings back the self-belief which must have been wavering after the Tri-Nations, then it might just be an important stepping stone."
The Sunday Times said "a change in conditions, different returns from substitutions for the two teams, and good old-fashioned Irish pride saw a 14-man Springbok team make it by the skin of their teeth."
"South Africa arose from the Tri-Nations canvas to produce a heart-stopping victory... they restored pride in the Springbok jersey with a display of raw guts and bloody-minded refusal to lose," said The Sunday Independent.
The Springboks face Wales, Scotland and England on the next three weekends as they seek a fifth 'grand slam' over the home unions, before wrapping up the tour with a game against the Barbarians in London in December.