Greatest ever test bowler?

In cricket we tend to look at career statistics when deciding who is the best at something. For example: Don Bradman averaged 99.94, and so he's the greatest batsman. But there's something fundamentally flawed in this concept. It assumes that a player has a certain level of ability, and that that remains constant throughout their career. That assumption is patently ridiculous once it's broken down.

If Don Bradman had made a comeback in his 60's, and played 10 tests at an average of 40, it would have added to his reputation, but subtracted from his career average. It would not have changed how good he was either side of World War 2. 

Likewise, looking at something like total wickets fails to take into account the differences in scheduling. It is a fine way to compare two players who played for the same team, but across teams the schedules are just too different. In the last 15 years, England have played 190 tests, while New Zealand and Pakistan have played 118 and 119 respectively. Hence, if an English player had played roughly 80% of their team's tests in that time, and taken 3.2 wickets per test (based on Fidel Edwards career numbers) they would have taken about 480 test wickets. If a New Zealand or Pakistani player had done similarly, but taken wickets at roughly 4.7 wickets per test (ala Dale Steyn) they would have roughly 445 wickets. Taking more wickets is inevitable when you play more matches.

To counter that, people talk about comparing players at their peak. Who reached the highest in their career?

I decided to have a look at just that. This list is lacking context - it hasn't accounted for opposition or conditions, but I think it's more useful than looking at overall career statistics.

This is the list of bowlers based on their best 30 consecutive matches.

This is still not perfect. For some of these players, 30 tests was just over 2 years (eg Botham, McGrath, Anderson) while for others it was more than 5 years (Steyn, Lindwall, Briggs, Laker). It's likely to be able to maintain peak form for 2 years easier than over 5 years.

It made me wonder if 20 tests was a better measure.

The same problem is here too. It took 8 years for Bobby Peel to play 20 tests, while McGrath and Pollock both took less than 2 years to do it.

However, the name at the top remains the same. Imran Khan has a greater claim to being the best ever than I would have realised.

There are lots of problems with using this as a canonical vaule for the best ever. But I think it's better than career stats, and certainly adds something to the conversation.