South Africans' first-class career bowling averages during Isolation (11/3/1970-17/4/1992). Qualification 400 wickets.
van der Bijl 717 wickets @ 16
Procter 1070 @ 20
Hanley 408 @ 20
le Roux 838 @ 21
Rice 898 @ 22
Donald 466 @ 23
Kourie 421 @ 23
Clift 876 @ 24
Kenny Watson 446 @ 24
Jefferies 469 @ 27
Anton Ferreira 583 @ 30
Ontong 836 @ 31
Also: Barlow 368 @ 21, Hobson 374 @ 27.
Unofficial Tests involving South Africa 1982-90. Qualification 25 wickets.
Sylvester Clarke (WI) 37 wickets @ 16
van der Bijl 29 @ 19 (first match a week before 34th birthday)
Rice 28 @ 22
le Roux 59 @ 23
Rackemann (Aus) 34 @ 24
Jefferies 39 @ 29
Kourie 38 @ 33
English first-class bowling averages 1980. Qualification 65 wickets. (This was van der Bijl's only season in English first-class cricket, aged 32)
van der Bijl 85 wickets @ 14.72
Jackman 121 @ 15.40
Marshall 66 @ 17.72
Emburey 75 @ 20.24
Sylvester Clarke 79 @ 21.51
Daniel 67 @ 21.70
Hemmings 77 @ 22.07
Graham Stevenson 72 @ 23.18
Nash 74 @ 23.28
Nick Cook 75 @ 24.74
Tim Lamb 66 @ 26.13
Doshi 101 @ 26.73
Also: Garner 49 @ 13.93, Hadlee 29 @ 14.13, Imran Khan 54 @ 17.90, Procter 51 @ 18.25, Lillee 20 @ 19.55, Rice 39 @ 22.02,
Underwood 61 @ 23.24, Roberts 27 @ 24.33, Holding 44 @ 24.90, Croft 25 @ 27.60, Willis 49 @ 27.87, Botham 40 @ 34.67.