A good wicket keeper takes their chances, scores runs, and doesn’t allow many byes.
Only one of those can be easily measured – we use the batting average.
For the others, a proxy will have to do: percentage of team dismissals (measuring ability to hold catches), and byes per hundred overs (in lieu of measurement of fielding errors).
Here’s a chart showing those three measures (the larger bubbles are higher batting averages).
Now we are getting somewhere. The ideal player is at the top left with a big bubble. AB de Villiers wins. There’s insight in this chart, Adnan Akmal’s career passed me by – but through the above we can see a decent gloveman, albeit not up to the batting requirements of Test cricket.
How about comparing players? De Villiers beats Mushfiqur Rahim on all three measures. But what about Tim Paine vs Sarfaraz Ahmed? We need to apply a weighting to each factor. Here’s my estimate and why:
- Byes: runs impact = Byes/100 overs*1.62 because there are 162 overs in the average match.
- Average: runs impact = Average * 1.48 (because the average wicket keeper is dismissed 1.48 times per match.
- Percentage of team dismissals: runs impact = (% team dismissals – 28%) * 146.5 (I’ve estimated 4.5 dismissals per match for the keeper that takes 100% of chances, which would be 28% of team dismissals. At 32.6 runs per wicket, the perfect keeper is worth 146.5 runs more than a non-catching keeper. All keepers are between 0-146.5).
Here’s the same players ranked according to those weightings:
AB de Villiers is comfortably the Red Ball Data Wicket Keeper of the Decade (RBDWKotD). I’m sure he’ll be chuffed. Was he flattered by averaging 59 with the gloves? No – he averaged 57 overall this decade.
There are secondary effects which one could measure (for instance, a left handed first slip taking chances from the keeper, reducing the number of dismissals). One might also want to consider intangibles, such as the ability to be distractingly inane, or contribute to strategy. These are judgemental, and I’m not qualified to opine on them.
There’s a point at the end of all this. Should Ben Foakes be in the England team?
Wow, that’s surprised me. It has changed my mind – I was expecting this to vindicate the selection of Jos Buttler. If Foakes is as good a keeper as we are told, it is sufficient to outweigh his inferior batting. There is little to choose between Jonny Bairstow and Buttler. Note that the usual disclaimer applies: need at least 20 Tests to judge, and only Bairstow has hit that threshold. Oh, and I’ve used my (more detailed) batting ratings for this chart, while Fig 2 uses averages while keeping wicket in Tests.