Wicket keeping averages, again

From Cricinfo 6 Aug 2010: "All told, [Kamran] Akmal has dropped 34 chances in his last 28 Tests, and he averages less than 17 in Tests against Australia, South Africa and England."

A wicket-keeper is a specialist fielder with gloves on, and should not drop chances. Each dropped chance is an extra wicket needed = (with ten wickets needed to bowl out a team) an extra 10% of that innings's runs (on average).

Ideally, a wicket-keeper's career batting average would be:

Runs - (Byes + runs conceded from dropped catches) / Innings given out


But the runs conceded from dropped catches can, alternatives, be approximately calculated from the overall test match bowling average for that era.

Currently each test match wicket costs an average of about 32 runs. Akmal, with 34 dropped catches, has therefore given away approximately 34 X 32 runs = 1088 runs in 28 tests = 39 runs per test.

Giving away 39 runs per test (plus, probably, quite a few byes), or nearly 20 runs per innings - Akmal would need to have nearly 20 runs taken off his average to give a realistic measure of his contribution to the team.

So Akmal has been worth minus 3 runs per innings to his team - so that any competent wicket keeper who did not drop catches would have been worth more - even if he scored no runs at all!

But even if Akmal had batting average of forty, then this would only translate to a real average of about twenty.

My point is that a wicket keeper who drops chances frequently is *very* unlikely to be worth his place - even if he is a good batter. A reliable keeper who never drops catches would only need to average about mid-twenties in order to be preferable to almost any imaginable unreliable batsman-wicket-keeper.

In other words, the traditional idea of choosing the best wicket-keeper is probably the best idea - and the modern idea of the batsman-wicket-keeper is basically flawed: a result of inadequate statistics.