I don't think Lukas statement that the Oat job board shows when Oat alumni change jobs is true. I suspect some graduates take a year or more to find work, so when their name suddenly pops up on the board, it might appear that they have moved to a new job, when it is actually their first one.
I've heard this as well. It might not be true for all of them, but for the Lufthansa ones it definately is.