Because the game state called for it, Preston were 1-0 up and were giving us the ball. This allowed Ethan to come into the middle as they had no threat down the flanks sat in a low block.
Matos has proven himself to be adaptable in game (just as Klopp is) but the system will more often than not be the Liverpool one which is the RB playing inside.
Key and Lissah offers us the other type as and when needed, but that is the secondary plan and not the primary.
I have no argument with those that prefer Ethan to play in the middle, it’s personal preference. It’s when people say he’s being played out of position, being caught out of position or doesn’t offer balance is what I am arguing against.
Being caught out of position suggests he shouldn’t be where he was when the possession was turned over, but being in the middle is exactly where he should be in this system on a quick turnover. His positioning is by design not a lack of positional awareness as others have said.