I don't deny that doping still goes on, but people are forced to resort to less effective means than they used to. Take the example of Rashid Ramzi--it is likely that he was not the only doper, just a more aggressive one. Why was he caught when others were not?
> speeds haven't really slowed down
This isn't wholly true. Have you seen a 3:26.00 1500m, a 7:20 3000m, or a sub-12:40 5000m lately?
It's also untrue that athletics doesn't have a biological passport system. There are bans being handed out now for passport violations. https://en.wikipedia.org/wiki/Natallia_Kareiva