Since the first international T20 game was played on February 17, 2005, runs and wickets have occurred in ODIs at the rate of 242 runs and eight wickets per 50 overs. In international T20 games runs and wickets have occurred at the rate of 146 runs and seven wickets per 20 overs. These figures are based on ODIs involving only the top eight Test-playing nations (excluding Bangladesh, Zimbabwe and the Associate teams).
As a point of comparison, since February 17, 2005, it has taken 107.3 overs on average for ten wickets to fall in a Test, at a cost of 328 runs. Since the first international T20 game, batsmen have been dismissed once every 18 balls in T20, every 37 balls in ODIs, and every 65 balls in Tests. Since all rules except for over quotas and the length of innings are identical across formats, this is a useful baseline.
One of the claims about T20 is that it produces a greater proportion of exciting finishes. This is conventionally taken to mean that more games are decided in the last over, or that the outcome is still uncertain in a larger proportion of T20 games until much later in the contest than in the other formats.
This view has its limits. The shorter the format, the greater the effect of each individual delivery, and therefore the greater the potential of each individual delivery to influence the state of the game. By this logic, a five-over game will be more "exciting" than a 20-over game. But are T20 games on average closer than ODIs or Tests? Test matches are not zero-sum games - they allow a third result, the draw. A draw does not imply parity, despite the implicit claim to this effect in the ICC's Test ratings. A draw is merely an inconclusive game. Let's set Test cricket aside for now.
The margins of victory in T20 and ODI cricket are revealing. Successful chases have been more frequent in ODI cricket than in T20; chasing teams win about 8% more often in ODIs. Nearly one in three T20 internationals has been decided by fewer than 7 runs (that is, by a margin of one hit) or in the final over, while only one in seven ODIs is decided in this way.
Eighty-five per cent of T20 chases are completed with five or more wickets to spare. The corresponding figure for ODIs is 70%. In an earlier post I showed that compared to T20, a larger share of the bowling in ODIs is done by good bowlers. The fact that chases are less successful in T20 than in ODIs, combined with the above facts, suggests that the practice of picking bits-and-pieces players who can hit the long ball in T20 may hurt chasing teams.
This is also apparent from the fact that lower-order batsmen seem to be able to steer a higher share of chases in ODIs than they do in T20s. However, keep in mind that the rules of dismissal and the rules for allotting runs are identical in T20 and ODI, and so the lower run rates in ODI cricket may work in favour of lower-order players.
One in five ODI chases are completed with at most three wickets to spare. In T20, one in ten successful chases is completed with 7 or more wickets lost.
For games won by the team batting first, I calculated the margin of victory as a percentage of the target. The higher number of last-over finishes in T20s are obviously by virtue of the small number of overs. As a share of the target, the distribution of results is not dissimilar in the two limited-overs formats. (This data also considers only matches involving the top eight Test-playing teams from February 17, 2005 to April 1, 2014.)
The closest 10% of ODI matches won by the team batting first (33 matches) produced a margin of victory of upto 4.4%. The closest 10% of T20 matches won by the team batting first (12 matches) produced a margin of victory of up to 2.7%.
The data for the two charts above is in the table below.
The closeness and excitement of T20 games seems to be an artifact of the number of runs that can be scored off a single delivery and the small number of deliveries available for teams to play with. This also produces a greater role for luck (since, for example, the value of a single lucky edge to the boundary is much greater in the shorter format).
There is further evidence that shows the enhanced role of luck in T20 compared to ODIs. Since the start of T20, the strongest ODI side has won 65% of its games, while the weakest has won 28%. The strongest T20 side won 57% of its games while the weakest team won 39%. (These figures do not include games involving Bangladesh, Zimbabwe or the Associate Members.)
The record is similar if we only consider the last five years. The strongest ODI team won 62% of its games, while the weakest won only 27%. The strongest T20 team won 57% of its games while the weakest won 40%.
While weak teams tend to be weak in both T20 and ODIs, they win significantly larger number of T20s than they do ODIs. This suggests that the consequence of individual risk-taking paying off is greater in T20 than in ODIs.
So what is to be done? Bad teams win T20 games more often than they do ODI games. Fortune plays a larger role, bad bowlers bowl more in T20, bits-and-pieces players play more. The excitement of the final-over finish, which basically comes about due to the length of the contest and not because of anything either team is consciously doing. (It never does; no team plays to make games closer rather than to effect easy wins, notwithstanding MS Dhoni's apparent interest in taking run chases to the final over).
Is cricket possible over 20 overs? I think it is if the shortening of the game is managed well. I propose the following for T20:
1. Double the over quotas for each bowler to eight per innings. This will result in teams favouring better bowlers, and better batsmen.
2. Eliminate the batting Powerplay. Instead, introduce a bowling Powerplay of five consecutive overs in which the fielding side gets to play three additional fielders, giving the fielding captain 12 fielders to play with, instead of nine. This Powerplay should be taken at a time of the fielding captain's choosing. Substantively, allowing more fielders is not different from limiting what parts of the field can be patrolled by fielders. The latter has been common in all cricket since Bodyline at least.
3. During the remaining 15 overs of the game, the fielding side will have to revert to playing with 11 players (nine fielders). But during this time:
a) A boundary will be worth two runs instead of four.
b) Hitting the ball over the boundary will be worth three runs instead of six.
c) Missed catches or missed relay throws that cross the boundary will be worth four extra runs (or six in the case of a missed catch where the ball is parried over the boundary).
4. Give the batting side a maximum of six wickets (eight batsmen) to play with over 20 overs. (I will present evidence in a forthcoming post which shows why six wickets is a good number. Currently, I will point to fact that 6.7 wickets fall per completed T20 innings on average).
These rule changes will hopefully produce the following consequences:
1. Fielding captains will have more resources to play with.
2. Power-hitting will be rewarded, since hitting fours and sixes against better bowlers and 12 fielders increases the difficulty of hitting boundaries. Reducing the runs that accrue for reaching the boundary at other times increases the value of being able to reach the boundary during the Powerplay.
3. There may be the possibility of scoring more runs within the field of play than by hitting boundaries for 15 of the 20 overs.
4. Teams will have an incentive to play the best bowlers and best batsmen they can find. The incentive to compromise will be minimal.
Overall, shifting the balance towards the fielding side using the rule changes that I propose will produce a contest between bat and ball that is better balanced and might create measures of merit beyond outcomes in individual cases. This will go a long way towards making T20 a sport like cricket is.