Dennis John, who assisted Australian Alex Evans at the 1995 World Cup - scene of Humphreys' first Test in charge - said current coach Steve Hansen had little choice but to select the veteran frontrower.
'I was a little surprised by the news, but when you look at the injury crisis among the hookers, you can see why it was done,' John said.
'I've seen Jon play only once for Bath this year, but he played very well. He'll bring bags of enthusiasm to the job and he always gives 100 percent.
'The thing with Jon is that players respond to him, so I hope they will on Saturday. Hopefully, the team will give it their best shot - that's all we can hope for.'
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Humphreys, 34 next week, captained Wales 17 times between 1995 and 1997 but he last represented his country during the 1999 World Cup.
Former England coach Jack Rowell has also backed his leadership qualities.
'Joining Bath Rugby has relaunched Jonathan's career, as we have seen through his performances for the club this season,' said Bath's director of rugby.
'His leadership qualities are very evident, and thus in Wales' time of need, it is no surprise that they have recalled him as hooker and as captain.
'We wish him all the very best of luck on Saturday.'