It depends what the skater wants. If Davidov stayed in Russia, he may not have had the same opportunities Euros/Worlds as he had. He went to Olympics twice, which he would not have been sent if he didn't change countries. (The fact that he didn't grab this opportunity and had better result is another matter, but he can't blame anyone for that. That's his fault.) He may not be happy about the change of country now, but it did help him compete at the highest level. And in regards to being stuck with Belarus passport, in doesn't prevent him having succesful coaching career.I wanted to comment on this part, since I read an interview with Davydov recently. And he sounded like he was neither too fond of how his skating career turned to be, nor was he happy being stuck with Belarus passport. He's a coach at Sambo-70 now, and a fairly successful one at that. He is leading a strong junior group and his girls get a fair share of Grand Prix assignments. But while Belarus citizen enjoy unrestricted residence and work rights in Russia, it still is an impediment in his coaching career.
So I'm not telling that choosing to represent a different country is strictly wrong and nobody should do it, but this isn't something you just do, and it's a decision that comes with long term consequences.
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