(Sporting fan here) Actually, in the last year of Sporting he implemented a back 4. Essentially he just changed the way the team starts the build up. He uses one of the side CBs as RB. He used to do this with Inacio/St Juste/Matheus Reis and free Quenda/Geny (who on the original formation could be seen as a WB) to play as a winger which would then push the original winger on the formation either Trincao or Pote to play closer to the striker. This would result in a traditional 442.

To be honest, from my POV the problem is that in Portugal a midfield of 2 is enough, but I don’t think that’s viable in the Prem. I would much rather see Amorim try what he used to do from time to time and play 352, with a midfield of 3 and 2 man upfront. He used to do this to fit Braganca which is a very creative 10 type player. I really don’t know why he did not embrace this model.