A few observations
The high percentage of "bowled" and "stumped" dismissals in the first two periods can be largely attributed to the practice of the wicketkeeper standing up even to fast medium bowlers. This made bowlers bowl a straighter line as opposed to the current fashion of bowling in the "corridor" outside off-stump.
[[
Ananth:
Good point. Although a "straighter line" should also have resulted in increase in Lbws. Probably the laws prevailing at that time might have accounted for this.
]]
However, a straighter line should have translated to a lower strike rate and a higher economy rate among the fast bowlers in the early periods. But we observe exactly the opposite. The strike rates of fast bowlers have reduced while their economy rates have worsened over the years.

What's surprising is that left-handers have a higher batting average than right-handers at each batting position from 1 to 9 (it's only close at number 4, while right-handers do better at 10 and 11). This suggests it's not just the elite players driving the difference. Are left-handers systematically undervalued?

Note that lumping the first 35 years of Tests together glosses over perhaps the most important period of change in the game, that occurred in the 1890s. 1895-1913 was called the "Golden Age", with some justification, whereas in 1877-1895 cricket was extremely slow and dull by modern standards. These two periods should not be averaged together.
[[
Ananth:
A valid point. However I was also trying to cut down the number of periods. For instance the 2000s might very well, one day, need to be split into Australian-domination and Australian-going-down eras since there are likely to be distinct changes.
]]

The run rates for spinners did not change much over time, but it changed a lot for fast bowlers. That, I think, can be attributed to the protective gear batsmen now don when facing the quicks. That's a lot more edges reaching the boundary, edges on balls players from the 60s and 70s might have avoided in the interest of safety.

forgive me for sounding impolite. While this article was quite informative it was an utterly boring read. Isn't there a way by which author could use more imaginative ways of presentating rather than just dump us with numbers. I feel such analysis takes the life out of the game that we love and makes it look so ordinary and insipid. I appreaciate the amazing effort that has gone into building these humungous databases, but can't they be put to better use. Thanks.
[[
Ananth:
It is obvious you have no time for understanding Cricket history or its evolution. I am sure there are much better and not-so-boring reads or broadcasts for you. In the meanwhile you are welcome not to waste your time on such useless articles.
]]

On lefties: There was a paper by Brooks et al. that looked at the 2003 World Cup, and it provided some evidence that lack of familiarity is the reason for left-handers being so common and successful at the top level of the game.

Basic idea: in low-level competitions, the raw talent is varied enough for there not to be a noticeable advantage for lefties. But in competitions where the talent spread is small (ie, a strong cricketing country), the advantage of being a lefty (and hence unfamiliar) becomes more significant, so you get more and more lefties at the highest level. But presumably not more than 50%, or the righties would start to have the advantage.

Anyway, in the 2003 WC, lefties and righties did similarly against bowlers from the best teams, but lefties did much better than righties against bowlers from the minnow sides (who bowl in leagues where there aren't many lefties).
[[
Ananth:
David, my feeling is that analysis will bring out different results for ODIs and Tests.
]]

One more possible factor for lower averages of right hand batsmen is that tail end batsmen predominantly tend to be right handers(i am assuming that by batsmen you mean the entire eleven and not just the top seven or eight)

one more area of analysis could have been the increasing role of keepers as batsmen, though it is pretty evident.
and ya, the stumpings have come down because the batsmen nowadays tend to stay in their crease. Part of this is because of the enormous power they generate from the crease and the new bats, and also the reluctance of the spinners to flight the ball and draw the batsmen out of the crease.
[[
Ananth:
You are right. I did a 100% analysis. It is possible that a sub-analysis can be done for batsmen like what I have done for bowlers (separate for bowlers > 100 wkts). When I do that I will incorporate the same within the main article. So pleas look for the same within the next 24 hours.
]]

and if the record keeping permits, we'd love to have an analysis of the percentage of runs scored in boundaries. It is always an interesting means of figuring out the mindset and nature of the batsmen, the captains(who set the fields) and the teams(attack or grind).

all in all, this is one of the most comprehensive analysis I have come across. Great job!

This is a response to Hariharan Sriram's comments.

I have added a sub-analysis of batsmen who have scored over 1000 runs and the results are provided below and have been added to the main article also.

All->1000R 37.34 39.46 37.90 |28413 2716 959557|10062 929 360365|38475 3645 1319922

It can be clearly seen that the difference between Right and Left handers is less pronounced with this tweak clearly substantiating Hariharan Sriram's observation.

This has also been incorporated in the main article.

Many thanks to him.

With regards to the high "Bowled" % in the pre-war period, I think the pitches and the style of bowling must have had something to do with it. The slow bowlers seem to outnumber the quicks in those days, with Australia having the likes of Boyle and Parker bowling with great effect and only Spofforth being really quick. Likewise England with Lockwood et al, and South Africa with Faulkner & Friends. This type of bowling, on pitches that could get good and wet and have the ball skid low, evidently did result in a lot of bowlings.

One more possible factor for higher averages of left hand batsmen may be bowling angle. The number of right hand bowlers is more than left hand bowlers and a right hand bowler's natural angle for a left hand batsman is to move the ball away from him. This decreases the possibility of getting out.

I think one contributing factor to the higher averages of left-handers is their reduced likelihood of being dismissed lbw, considering that bowlers, just like batsmen, tend to be right-handed. Right-armers bowling to left-handers will be denied lbws more often by pitching outside leg (just as we see - but less often due to their scarcity - with left-arm quicks bowling to right-handed batsmen). Furthermore, if they go round the wicket, the angle they create means they will often be missing leg if they hit the batsman in line. In short, there's no better chance of an lbw than when a right-armer bowls to a right-hander (or left to left, but again this is far less common). Of course, I don't believe that this fully accounts for the significantly higher averages of left-handed batsmen, but I'm sure it represents a piece of the puzzle.

I think one of the reasons why lefties do better is that they are always going against the grain. Most bowlers are righties who have to make adjustments against batsmen lefties, ie going around the wicket. I would suggest that an analysis of tennis lefties that do well is also proportionally better than righties. I would love to compare lefty bowlers against lefty batsmen and righties against righties. Also a combination of left and right batsmen at the crease interchanging continually also destabilises the fielders, who have to adjust positions after every odd run.

A common response to the fascinating insights being provided by the readers regarding the superior averages of left-handers. All these make sense and together contribute to the overall better performance of left-handers.
The comment on the angles being employed is very valid.
It is true that the angle of an outstanding left-hander such as Nadal seemed to be the only way to stop, or rather slow down, the incomparable Federer.
It is impossible to do a left vs left analysis owing to non-availability of ball-by-ball data.

I don't think the reduction in run-out % is due to 3rd umpires or technology because these were only introduced in the 90s, and there is very little change from the 80s on.

I think the most likely reason would be the introduction of one-day cricket, which would have improved players' skill in running between the wicket.

Another possible measure could be the successive differences in team totals between each of the four innings which might throw light on pitch preparation; a steadily decreasing total from 1st to 4th might tell of decent pitches which deteriorated at a normal rate, huge differences between the first and second innings totals of teams might either speak of dry pitches which crumbled rapidly or damp strips which eased out under the sun; Although I understand that pitches were rarely covered until 1974 or something, so the analysis might be a bit flawed.

Another possible measure could be the successive differences in team totals between each of the four innings which might throw light on pitch preparation; a steadily decreasing total from 1st to 4th might tell of decent pitches which deteriorated at a normal rate, huge differences between the first and second innings totals of teams might either speak of dry pitches which crumbled rapidly or damp strips which eased out under the sun; Although I understand that pitches were rarely covered until 1974 or something, so the analysis might be a bit flawed.

Ananth: Two reasons why LBWs remained uncommon in the early periods despite the straighter line of the bowlers (apart from the differences in rules)

- Batsmen seldom used their pads unlike in the post war period when pad play became very popular especially when facing spinners.

- Batsmen weren't too adept at flicking straight deliveries across the line, which reduced the incidence of LBWs. This is just my hunch, based on the old 1930s newsreel footage I've seen. I generally find players of that period offering the full face of the bat even to deliveries on middle stump. One day cricket has definitely improved the range of strokeplay, especially the art of hitting across the line. Subcontinental batsmen with their wristy unorthodox style have also contributed to this.

The increase in keeper catches could also be attributed to keepers being much more athletic these days (ie more difficult, diving catches)