How good are they?

A player's performance - both current and career-long – is under constant scrutiny by the statisticians.


Performance in a single match
Assessing a player's career


Performance in a single match

There are certain landmarks that cricketing custom deems significant in a match. These are:

• Scoring 50 runs, or any multiple of 50, as a batsman
  
• Taking five wickets in an innings, or 10 wickets in a match
  
• Passing a record (either the player's own record, or a record set by someone else).

These achievements bring applause from the crowd, although players who score lots of 50s but fail to convert those 50s into 100s are often regarded as somehow under-achieving.

The statistics of a player's career invariably record how many 50s and five-wicket hauls the player achieved. However, the raw statistics rarely tell the whole story. The context of a performance is also important. Take the following innings, for example:

Mike Atherton (England versus West Indies, second innings at The Oval in 2000) scored 108 runs. He has often scored more runs than this, but the commentators at the time described this innings as one of his finest, 'worth a double century in normal conditions'. What did that mean?

• It had been a low-scoring match, which was an indication that run-scoring was difficult. England were bowled out for 281 and 217 in their two innings, making Atherton's 100 very significant.
  
• More than half of the overs were bowled by Ambrose and Walsh, two of the best bowlers in world cricket. Scoring runs against top quality bowling is much more difficult than against run-of-the-mill bowlers.
  
• The match was extremely tense. If England were to lose then the West Indies would tie the series. Thanks in part to Atherton's batting, England went on to win the Test.

So for all of these reasons, Atherton's innings was a truly great one.

There are some cricket statistics that do attempt to mathematically evaluate an innings using more than just the batsman's score, for example:

• Channel 4's World XI game gives a batsman extra credit for scoring a high proportion of his team's runs. Click here for the formula.
  
  
• The PwC Ratings, often quoted as the unofficial world rankings of cricket, go even further. They adjusts both for the proportion of runs in the match, and the ratings of the opposition bowlers. PwC rated Atherton's century as his best ever Test innings, even though it wasn't his highest score.

Assessing a player's career

Players are not usually assessed on the basis of one match, but more on their entire career. There are many ways of rating a Test player. To show this, here are some real statistics for several current Test batsmen as at 1 July 2001:

	Runs in career	Innings in career	Not outs in career	Runs in 2001	Completed innings in 2001
Mike Atherton	7507	202	7	227	9
Sachin Tendulkar	6919	135	14	503	9
Brian Lara	6533	141	4	463	12
Graham Thorpe	4476	124	16	497	7
Venkata Laxman	1438	43	3	604	10
Matthew Hayden	1085	28	1	557	7

Different methods of calculating the rankings lead to different results. Some of the results make more sense than others - what often happens is that commentators select the ranking that supports their argument!

A more sophisticated ranking needs to make allowances for players who are normally great, but have suffered a setback in their form very recently (Atherton for example). To do this, we need a weighted average that gives more credit to recent form but doesn't ignore past greatness. A simple weighted average can be worked out like this:

Runs in 2001 count 100%
Runs in 2000 count 50%
Runs in 1999 count 25%
Runs before 1999 count 10%

However, it is a little arbitrary to say that 100 scored on 1 January 2001 merits twice as much credit as one scored a week earlier.

The PwC World Ratings use a more sophisticated average that decays each innings by 4% as you go back in time. This smooths out the jumps in the earlier example and works like this:

Most recent innings counts 100%
Previous innings counts 100% x 0.96 = 96%
Innings before that counts 100% x 0.96 x 0.96 = 92.2%
Innings before that count 100% x 0.96 x 0.96 x 0.96 = 88.5%
And so on.

In the PwC system, players' innings are also weighted according to the opposition strength and run levels in the match. By this calculation the batsmen rank as follows:

Tendulkar

Lara

Thorpe

Laxman

Atherton

Hayden