Scotland head coach Gregor Townsend was disappointed to lose Tandy, whose appointment has split opinion on social media.
Views range from people being underwhelmed to others saying he is the right man at the right time.
Tandy, 45, knows Welsh rugby always provokes debate and the former no-nonsense flanker will need a thick skin to deal with the role.
Some have gone as far as to suggest this is an impossible job, but Reddin disagrees.
“From my perspective, I don’t think it’s impossible at all,” he said.
“Are Wales going to be consistently ranked as the number one team in the world for the next 10 years? No, I don’t think so.
“But can we be a genuine, top-five nation who are constantly competing for Six Nations titles, capable of mixing it with the best in the world? 100%. Otherwise, I wouldn’t be here.”
Tandy will have to win over the doubters and the only way to do that, in the long-term, will be by delivering results.
Given the dire situation Tandy is inheriting, that will be the ultimate test. Reddin says he hopes to provide Tandy with the tools to succeed.
“I don’t think anybody gets inspired by a team that says, ‘well, we’re going to rock up and do our best’,” said Reddin.
“Especially a passionate rugby nation like Wales, we’ve got to be more ambitious than that. Passion on its own is not enough, it’s useless.
“You’ve got to get all the other bits right as well. If you’ve got those bits right, the passion can carry you somewhere special.”
Welsh rugby will hope Tandy will be the man to deliver on such bold sentiments.
