Turning it around, I think the worst ever pairing was when David Harmon was pulled out of the Giro coverage at the last minute in 2013, and his replacement was Declan Quigley who up 'til then had done a bit of cycling commentary for the Tour Series and not a lot else. Kirby and Hatch were unavailable (Hatch doing other things for ES like Dunkirk, Kirby off in Italy for RCS). So Quigley, who really was the student learning the Euro peloton on the job, had Kelly for company for 3 weeks. My god. I really like Quigley - I liked him from the Tour Series stuff I'd seen before and I've grown to like him again on ES, but it was painful viewing at times during that debut year. But that Giro... it really was something.
https://www.youtube.com/watch?v=1OtEfFkt6GI (Girl Stage 1 2013)
And as an aside, Harmon's swansong - I'll never forget this commentary from the week before when the (later to be exposed as EPO-fuelled) Torku rider ripped it up and DH lost it (as did big Maggy).
https://youtu.be/OXONaRGVOB0?t=1h19m36s