If you notice ETH's signings, he always made huge emphasis on ball possession. Martinez is a superb passer of the ball with 92% passing accuracy, Eriksen was in the 90%, Casemiro had 86% accuracy in La Liga and Mount has 85% passing accuracy. So what I think went wrong?
A- Similar to LVG, ETH completely ignored how physical and intensive the EPL is. Take a look at his signings. Martinez is 5ft9 ie he's shorter then Gaz is, Malacia is 5ft7 ie just an inch taller to Scholes, Anthony is 5ft9, Mount and Eriksen are 5ft11. This is a short side which in turn makes them less physical and more likely to get bullied when they go toe to toe against a typical 6ft3 EPL giant. Which leads us to B
B- A manager can come up with many sexy tactics (high line, gegenpressing etc) but ultimately when there's a corner or a set piece to defend you need tall players. Martinez can act like a big boy but 9 out of10 he'll lose an aerial duel against a Tosin whose 6ft5. Thus ETH had to concede defeat on that. In short term that lead to the vast utilization of the likes of McT whose 6ft3 frame gave us some aerial cover + physicality. Another issue with shorter players is that the physical stress when going 1v1 against a 6ft5 defender tend to be bigger when compared with that of a player of their same size. Which lead to injuries, more reliance on Mou/Ole's players who, in turn, are not suited for ETH's ball possession game.
C- The sudden decline of Casemiro and Eriksen hurt us big time. We lost alot of workrate in midfield but also our pass accuracy nosedived. Casemiro went from 86% pass acc to 80% and Eriksen from 90% to 81.9%. Add to that the loss of Martinez + Shaw and the reliance of McT, Lindelof and Maguire who are hardly great passers of the ball hurt us badly.
ETH seem to have learnt his mistake. Mazraoui, Zirkzee, Yoro, De Ligt and Ugarte are all around the 6ft-6ft4 mark. In typical ETH's tradition they are all excellent passers of the ball. De Ligt 93.1%, Ugarte 91.7%, Yoro 92.16% and mazraoui 90% are a clear upgrade over Maguire and AWB (84%) and McT (82%). Then there's a clear upgrade in terms of aggressiveness and workrate. Zirkzee and Ugarte cover an astronomical amount of distance between them.
Would that translate into creativity? I don't know. Ugarte and De Ligt had been accused of being safe passers. That means that our creative players will have to do some heavy lifting there. What's certain is that if everyone remains fit (and that's a huge if) then you'll certainly not see hoof ball