Was that back when he was training with Steve Mullings?
Sorry, but if your favourite athlete trains with a doper, there is a good chance they are also a doper.
If your favourite athlete has a coach that was a doper, there is a good chance that they are also a doper.
If your favourite athlete has a coach that has trained other athletes that were dopers, there is a good chance that they are a doper.
If your favourite athlete has a coach that was involved with other illegal or other underhand practices, that is also a sign that they might be a doper.
Bonus points for any associations with quack doctors, like anti ageing specialists.
If even one of the above apply, you should not be surprised by a positive test.
If more than one of the above apply, then believing that athlete was clean is an act of faith, not logic.