So I've been working on a few ways to make this take longevity and team influence (wickets per match mainly) into account here so it's not just based on averages, and in fact of measure of how valuable a player's performances were throughout his career. I spent quite some time working on a formula I thought was fair to all eras of cricket and accounted for the changing nature of cricket scheduling, and implemented it into my system.
The results suggested that Jack Cowie was the greatest bowler, and fourth greatest cricketer, in the history of Test cricket. Eek. So much for that then.
The problem with that seems to stem from the fact that even though he only played nine Tests, they were over a twelve year period and in fact the only nine Tests New Zealand played. It treats him the same as, for example, someone who played for twelve years without missing a single Test for England between 1998 and 2010 - that'd be 167 Tests or so. And given his standardised bowling average ended up below 20 (better than Barnes or in fact anyone with a decent number of wickets), it's easy to see why I got the results I did with that. Not sure if it's worth posting them up until I find a way around that particular anomaly.