I managed to overwrite my old server's stats with my new one's (empty) stats. My fault, I suppose, but it could use some clarification over which way the migrate works, or better yet, warn you if you're about to "migrate" empty stats.

Which part was confusing to you?

There are two parts that help clarify currently,

1. The dropdown and button to perform the action indicate you are moving stats to the server you select.

2. The (?) button describing the feature tells you the implications of what will happen to the server you are currently on, as well as the server you select.