I watched Atherton quite a bit, throughout the nineties and if there is one thing I can really remember, it was that the commentators always used to say "Here's the wicket the opposition want to take" and with my hazy memory, I remember plenty of occasions that the opposition succeeded in taking his wicket early.
Atherton has two rather large technical flaws from my memory. Firstly, a good ball from a fast-medium bowler on an off-stump line would inevitably end up with him being squared up, edging the ball to the slips and with him being face on towards the bowler. This problem still arose in his prime, as I recall. The second problem he had was that he enjoyed chasing balls down the leg side. Quite often, these loose balls are profitable for a decent batsman, but I remember at least 3 times where Athers edged the ball and was dismissed of what was an otherwise innocuous delivery.
As a result, I fail to believe the hype that was generated over Atherton. In fact, the most accomplished innings of his I remember watching was his 99 at Lord's in 1993; I sat in the cheap seats lapping up the atmosphere of an Ashes test whilst poor calling from Gatting, and inadequate studs on Atherton's boots saw him slip over and run out 1 short of what would have been his only century for England at Lord's.
By the way, Richard. Does your first chance average take account of times where the batsman has been legitimately dismissed, but the umpire hasn't given it? There was that time where Athers scored a big hundred despite having edged to the keeper early on and not having been given. Surely, technically, that's a chance that should be reducing his first chance average??
Anyway, in conclusion, I wasn't a big fan of Athers. Played and missed an alarming number of times and was given a tremendous amount of hype by the English commentators. Tresco had his shortcomings but from a neutral perspective was a much better batsman to watch play.