All-rounders

An all-rounder is a cricketer who regularly performs well at both batting and bowling. Although all bowlers must bat and quite a few batsmen do bowl occasionally, most players are skilled in only one of the two disciplines and are considered specialists. Some wicket-keepers have the skills of a specialist batsman and have been referred to as all-rounders, but the term wicketkeeper-batsman is more commonly applied to them, even if they are substitute wicketkeepers who also bowl.

There is no precise qualification for a player to be considered an all-rounder and use of the term tends to be subjective. The generally accepted criterion is that a "genuine all-rounder" is someone whose batting or bowling skills, considered alone, would be good enough to win him a place in the team. Another definition of a "genuine all-rounder" is a player who can through both batting and bowling (though not necessarily both in the same match), consistently "win matches for the team" (i.e., propel his/her team to victory by an outstanding individual performance). By either definition, a genuine all-rounder is quite rare and extremely valuable to a team, effectively operating as two players.

Confusion sometimes arises when a specialist bowler performs well with the bat. For example, the great West Indies pace bowler Malcolm Marshall achieved ten scores of 50 or above in 107 Test innings between 1978 and 1991, but had a batting average of less than 19. He would be termed a "useful lower-order batsman". Equally, a specialist batsman may be termed a "useful change bowler" and a good example of this is Australian Allan Border, who in a Test match against the West Indies in Sydney in January 1989 took 11 wickets for 96 runs (7/46 in the first innings and 4/50 in the second) as the conditions suited his occasionally used left-arm spin.

One of the main constraints to becoming a recognised all-rounder is that batsmen and bowlers "peak" at different ages. Batsmen tend to reach their peak in their late twenties after their technique has matured through experience. Conversely, fast bowlers often peak in their early to mid twenties at the height of their physical prowess. Other bowlers, mostly spinners but also fast bowlers who can "swing" the ball, are most effective in their later careers.

...
Wikipedia