Spanish tactician Unai Emery has used a fluid 4-4-2 formation for most of the season. This formation can change during matches to a 4-2-3-1, 4-2-2-2, or even a 2-2-4-2 when the fullbacks push forward.
This tactic has been highly successful, with Villa currently in 4th place in the Premier League and with a great chance of qualifying for the Champions League.
However, there have been exceptions. When Villa hosted Tottenham Hotspur, Emery switched to a formation with 3 center backs and wingbacks on either side.
A big part of Emery's tactics involves playing the ball out from the back, which has worked well for Villa's defenders and Argentina's number 1 goalkeeper, Emi Martinez.
This change in defense meant that Villa had to pass the ball around in their own penalty area with players in unfamiliar positions. This tactic didn't work well, as Villa regularly gave the ball away and invited pressure. They conceded easy chances and ultimately lost the match 4-0.
Up next was a trip to West Ham. Emery tweaked the system again, opting to play with two out-and-out strikers: top scorer Ollie Watkins and Colombian wonderkid John Duran. This meant Villa had one less midfielder when trying to play out from the back. The defenders' options were limited when looking to pass the ball forward.
In the first half, West Ham caused Villa all sorts of problems and went into halftime 1-0 up. To Emery's credit, he made a substitution, taking Duran off. Villa came out in the second half playing their usual style with the extra midfielder for their defenders to pass forward to. They played much better and came away with a point after Italian attacking midfielder Zaniolo equalized in the 79th minute, with the game finishing 1-1.
These experiments with the formation haven't been successful. Hopefully, for the remainder of the season, Emery will stick with the tactics that have brought Villa so much joy since he took charge.