Does keeping influence batting?

My post a month and a bit ago about Matt Prior has generated a significant amount of interest, including one specific comment that I would like to address.

Unfortunately the poster was anonymous, but they recommended Sangakkara as the greatest wicket-keeper batsman, pointing out that he batted at number 3 and often had to come into bat in the first 5 overs. It made me wonder just how hard batting after keeping was. So I had a look at some stats...

I found 5 players who have played at least 10 innings as keeper and non-keeper: Here are their averages:

Name	Inngs keeping	Avg keeping	Inngs not keeping	Avg not keeping
AJ Stewart	145	34.92	90	46.70
KC Sangakkara	81	40.48	81	72.75
AC Parore	109	26.94	19	22.70
A Flower	100	53.70	12	35.45
BB McCullum	85	34.77	12	55.18

The last three in the list probably don't give us enough information to be able to say too much, although both Flower and Parore are curious in that they averaged better when keeping than not keeping. In Parore's case it might have been because he usually batted at 7 or 8 when keeping, and at 3 when not keeping. It also might have been that he was less confident of his place in the side when Lee Germon was the captain, and so did not bat with the same confidence. Another possible explanation was that the matches he didn't keep in were the ones where Glenn Turner was in charge of the team, and his style of coaching might not have suited Parore.

Likewise most of the matches where Flower didn't keep were at the end of his career where there was increasing political tension in Zimbabwe. This was obviously impacting him - and led to the famous black armband incident. (As an aside - Henry Olonga's autobiography, which mentions this incident "Blood Sweat and Treason" is well worth reading.) But he also might have batted better when he got a chance to have a look at a pitch after keeping.

But the overall theme of the statistics is that batsmen bat better when they are not keeping. Sangakkara is particularly astounding. His average of over 70 is impressive, especially as he is such a fluid batsman that all 72.75 of them will have probably flowed in an aesthetically pleasing manner off his bat.

It also goes to underline how fortunate we are to be living in a time with so many great wicket-keeper batsmen. All of Prior, Dhoni, Gilchrist, Flower, McCullum, Sangakkara... have been producing such remarkable numbers that they have transformed the entire position.