Collier-Keywood admitted his raw emotions after watching the Springboks loss which followed autumn defeats against Argentina and New Zealand and narrow victory over Japan.
“I felt very disappointed, very upset, it was hard to take,” said Collier-Keywood.
“I was embarrassed, yes. Any Welsh person sitting there would have been embarrassed.
“It was as bad as my worst expectations were. Inevitably you go into games and think about a range of potential outcomes, and that was probably at the worst end.
“I was concerned about the boys out on the field, it was clearly a massive mismatch.
“It shows you how far we have got to go.”
When asked whether the result gives the WRU more of a mandate to push through major changes, Collier-Keywood responded: “Absolutely it does. It was pretty clear to many of us before major change was needed anyway.
“We’ve got to reflect back on some of the positive changes Steve Tandy [Wales head coach] has made.
“You’ve seen a lot of that particularly in the Argentina and New Zealand matches this month.
“To snatch a win at the end against Japan was a great result and showed character.
“We’ve made progress and the disappointing thing, or the reason why I felt hardest about was going into the changing room at the end, was seeing the boys and how down they felt about it.
“Steve did a great job in trying to remind them of all the good things in that campaign, but that [South Africa loss] will have weighed heavily on their minds.
“I’ve been told by others, who have played professional rugby, you need one good thumping in your life to work out how far we’ve got to go and inspire you to reach the heights. But that would have felt tough.”
