As others have said, it's the not bringing in a replacement that's criminal. Add to that loaning out Gallagher with no recall option, and ending up paying £20m in January for someone who's not as good.
Today Tadic on the right, Redmond on the left, and a two man midfield was a recipe for disaster. Wigan should've been a warning sign, we got away with it because they were crap in front of goal. Bring in Romeu alongside PEH and Lamina, and move Tadic to the left. And the only place Redmond should be left is back home.