People who believe voter fatigue is a genuine reason for not voting for a player again.... Why?

I do not see this as a valid reason whatsoever to not vote for a player again.

If a player is great, the player should get your vote, regardless of what they did in previous years.

But if you are the type of person who DOES think this way..... What is your reasoning? Why do you think "I don't want X to win again, so I'll vote for Y, even though X is better" is a good argument?