Already discussed to death on multiple occasions in this and other threads.
WW was so easily marked and offered no threat running in behind Leeds defense, and in the channel. They was comfortably pushed their line high, and pressed compactly. This limited our out ball and made it difficult for us to build up. Most of our dangerous play was to/from left wing, which Garnacho end product left much to be desired.
WW off, and Rashford up top changed the dynamic of the game where we could easily exploit the space behind their high line from different angles. They were forced to back down and gave up most of their pressing game. Gave out more fouls, throw in, corner nearer to their box, beside us working our way in open play into crossing position.
WW was huge part of the problem. Perhaps, with full strength team, he could be carried to some extend. But he's an extra burden on top of the weakened team. Fingers should be pointed at him too. Not only to his teammates for issue with chance creation for this games, and the last few games where he started.