So what is the least suspicious for you?
I made my POV clear many times; the more constant performances are, the less suspicious. No hiding in far places, low on blood after transfusions, thus faking injury or whatever...
So Froome made his jump like few others before, but he did it at a relative young age and stayed at the top.
Up and gone, up gone, like CH, LA, Cobo, Mosq, DiLuca are way more suspicious in my eyes...
Now he could transfuse year around on a Sibiria system like TH described. If that´s the case he´ll be caught soon. You can´t hide such a complicated system that needs docs, fridges, secret hotel rooms, manipulating BP experts, forever.