Though Mike Moustakas' demotion is the big news of the day, he was already demoted in the hearts and minds of Fantasy owners, who are more focused on what seemed like a side note to everyone else: his replacement.
Danny Valencia has the potential to be ... OK. If he makes the most of this opportunity and doesn't force the Royals to seek out alternatives, he'll probably put up numbers somewhere in the Trevor Plouffe-Casey McGehee range. He's been far more effective against lefties than righties in his career, which may cause his batting average to tank over time, but at his best, he's a decent contact hitter with gap power.
As weak as third base his proven to be this year, that sort of player has value in Fantasy, just as Plouffe and McGehee have so far, but not as more than a last resort in leagues where corner infield spots have consumed much of the third base pool.
In AL-only leagues, Valencia obviously needs to be owned, but otherwise, he's probably not a game changer.