Very few fast bowlers in Test cricket manage to survive after their 33rd birthday, and those who do are clearly a special group. Since WWII, a total of 28 fast bowlers have taken a minimum of 40 wickets after turning 33, with 9 instances occurring since the turn of the century: Glenn McGrath, Chris Martin, Courtney Walsh, Ryan Harris, Andy Caddick, Jacques Kallis, Alan Donald, Mitchell Johnson and Chaminda Vaas.
Since 2000, just 36 fast bowlers have bowled a minimum of 10 overs after turning 33, and only 19 of those have taken at least 15 wickets. They have just 26 five-wicket hauls between them, while Courtney Walsh, Andy Caddick and Wasim Akram are the only three to have taken 10 wickets in a match.
As a whole, the 36 bowlers have taken a total of 1001 wickets with a collective average of 30.02 and a strike-rate of 63.27. However, Glenn McGrath, Chris Martin and Courtney Walsh have combined to take 35 per cent of those wickets. The trio are an aberration when compared to their peers. If you remove their numbers from the data, the collective average jumps to 32.58 and strike-rate to 66.39. The collective strike-rate for all seam bowlers after their 33rd birthday since WWII is 72.40.
For comparison, since 2000, 151 pace bowlers aged 28-32 have bowled a minimum of 10 overs. This grouping has taken 4329 wickets between them at an average of 29.51 and a strike-rate of 58.11. 72 have taken 15+ wickets, while there have been 152 five-wicket hauls and 16 ten-wicket performances.
One of the few bowlers who maintained his effectiveness right through a long career was Glenn McGrath. He averaged 25.48 in his first 29 Tests, but then moved up a gear and stayed there, averaging 20.59 through his next 95 Tests.
Courtney Walsh was perhaps the biggest aberration of them all as he averaged 25.86 in his first 30 Test matches and 24.09 in his next 102 Tests. His numbers after turning 33 were even better, with his average dropping to 23.64.
Similarly, Sir Richard Hadlee's average after turning 33 (20.33) was lower than his career average (22.29). Curtly Ambrose and Ewen Chatfield saw similar career arcs.
The following bar chart I created shows the numbers for the 19 seam bowlers who have taken a minimum of 15 wickets after their 33rd birthday since the turn of the century.
*image can be enlarged by clicking on it.
Dale Steyn and James Anderson - two of the games best fast bowlers to have made their debut this century - both just turned 33. Both have recently succumbed to niggling injuries which tend to plague bowlers after their 33rd birthday. Anderson has expressed his desire to carry on bowling at the Test level for another 5 years, while Steyn has given no indication that he is willing to hang up his boots any time soon. It will be interesting to see how both fare going forward.