Instead they were 3-0 down within half-an-hour, Pierre-Emerick Aubameyang (0.76) slotting home a penalty before setting up Kieran Tierney (0.06) to roll into the corner. Auba then scored an overhead kick (0.15) to effectively put the game beyond Watford before they had even had a chance to land a blow.
And yet as far as xG is concerned, Watford could and perhaps should have won the contest. Troy Deeney's (0.76) penalty evened things up and Danny Welbeck (0.54) closed the gap further but the chances that came for each are the ones that Watford could well rue.
Welbeck was denied twice by Emiliano Martinez in good situations, running in from the left to poke straight at the keeper (0.35) and then with a flick inside the area (0.55) that the keeper got down well to save, but should probably have been scored.
And Deeney's header (0.5) in injury time may well have proved to be academic - they needed to win to stay up - but it was still a glaring miss and added up to Watford winning the xG battle. 19 shots v Arsenal's 13, but in effect this came down to ruthless finishing, and Auba is one of the best in the business in that department.
What is xG check?
Each week FC will aggregate the Expected Goals (xG) ratings from three respected sources and provide an average for both the home and away team. From there we will assess which matches have ended in a different manner than the xG would suggest.
EXPECTED GOALS (xG) assesses the quality of a shot based on several variables such as assist type, shot angle and distance from goal, whether it was a headed shot and whether it was defined as a big chance. From there that shot is assigned an xG score and the cumulative total of these scores provides a team's xG for a match.Stats Definition
But sometimes, xG doesn't tell the whole picture, so we also analyse the highlights of these games to look at the chances created by teams in a little more detail.