Yeti, well there's "no pressure to participate" and then there's "no pressure to participate".
Blofeld gets all his henchman aboard his jet flying at 30,000 ft and says if anyone has a problem with his latest plan then they're free to walk away, no harm no foul, and good luck to you. Maybe he's telling the truth, but there's definitely some pressure there..
If the club messiah says to me, Prefect, we want you to go to this guy Dank and get multiple injections at an off site location which will help improve your performance. Its experimental but (probably) completely legal, just don't mention it to the ASADA guys. But you know, hey, if you don't want to do it then that's cool I'm sure everyone will understand.."
And then if the club President and CEO, and other people with power over my contract and team selection opportunities say the same thing, then the club can't say there was no pressure. Of course there was pressure, but the extent to which that pressure contributed to these guys making dumb decisions is the question.