Severino was actually going over to back up first as the run down was between first and second. The pitcher, who was not involved in the rundown, should have been covering third.
This video has a good overhead look. https://www.espn.com/video/clip?id=31647796
Galvis does a poor job of giving the ball up too early. Franco didn’t get to second in time, though there really isn’t too much he could do about that.
Actually, in a rundown, you should follow your throw so Mancini should have been going to second while Galvis was chasing Ramirez back to first. He instead went to first creating the hole at second.