If Champ manager ever taught me anything, it's that you adapt your formation to the players you have available, not the other way around.
All these one up front with two inside forwards formations are super-fashionable at the moment, but there's no point being fashionable if we don't have the players to do it properly.
To play like Liverpool or Man City you almost need your strongest players to be your wing-backs as they are expected to do the job of two players. Even the likes of Mendy, Alexander-Arnold and Alonso struggle with balancing their attacking responsibilities with actually occasionally needing to defend from time to time. Liam Palmer has proved a lot of people wrong in the last couple of years but he's never going to be the rampaging wing-back we need.
Bruce clearly started bringing the players in to try and play this system - Harris and Murphy fit the bill as quick inside-forwards that can cut inside and get shots in, Moses an attack-minded overlapping wingback. They were probably the best available without spending money, but I'm not convinced by two of them and I'm not sure we are there yet regarding being able to play the fashionable way.