The problem is, and I pointed this out when the change was announced, is that this is not a change for programming reasons, it's a change for 'diversity' reasons.
Jo Wiley is not there because Simon Mayo wants or needs a co-presenter, she is there because the BBC has decided that they need more women in mainstream programmes.
That is not a valid reason to thrust together two people who have individual audiences, in the flawed assumption that each individual audience will enjoy the two of them together.
Their individual audiences will not tune in - Wiley's because she is at home in an evening / specialist environment, and Mayo's because his approach is terminally hampered by having a 'co-host' with whom he is clearly not comfortable.
It was a bad idea, and hopefully the decision makers will bit the bullet, admit it was a bad idea, and go back to the previous set-up, which worked perfectly well and did not need changing.