Exactly.
We just lost Darren Gough who is 32 and has nearly 500 FC wickets at 26.
We are without Andy Caddick who is 34 and has 600-odd wickets at 24.
Richard Johnson is 28 and has 426 wickets at 26.
Compare this with:
Andrew Flintoff - 25, 81 wickets at 34
Simon Jones - 24, 95 wickets at 37
Matthew Hoggard - 26, 207 wickets at 26
James Anderson - 21, 65 wickets at 23
Steve Harmison - 24, 232 wickets at 31
Glenn Chapple - 29, 465 wickets at 28
James Kirtley - 28, 452 wickets at 25
These stats are based on FC wickets not including test wickets. So you can see there is a big difference. Gough and Caddick are season pros with hundreds of wickets to their names. Johnson and Kirtley have the advantage of being in their late 20s with approaching 500 wickets, but Anderson, Flintoff and Jones particularly, but also to a lesser extent Harmison and Hoggard have much less experience. They just haven't done enough bowling in county cricket, as Geoff Boycott points out.