When Reus is at home, going against people he knows he can beat, he feels confident, relaxed. This feeling allows him to get out in front and run his best race. In international competition, he is against people he knows are superior to him. This causes him to tighten up, not run his best race. Obviously he needs to overcome this. The clock doesn't lie. He is a ten flat sprinter. More international competition would be good for him. He would get used to it, then start to perform better.