The BBC News described Vicente as an attacking midfielder (=Trequartista)
I can't see Gus playing a true Trequartista (not that there are many I can think of in the game today anyway). Gus wants all of his players to contribute defensively, and I'm sure even Vicente will be expected to do the same. The trend now is instead for wide attacking midfielders that are happy to cut inside and support the striker(s).
Vicente to my mind will play the role currently occupied by Barnes. Playing down the right. But with license to interchange and drop in behind cms as and when the pattern of play requires it. This system can be. More rigid or fluent and flowing depending on the amount of possesion we're having. It can also double as a straight 4-5-1.
A far as I know El-abd is right footed, but he can whack ball out the ground with any foot.
I can't see Gus letting anyone have no defensive duties.
Which are the consequences of a Trequartista.
There is more than one formation that supports our style but they are all very similar and only have 1 centre forward. Normally it's more of a no.10 than a poacher and the finishers are the wide men cutting inside through channels.
Hopefully we don't do a newcastle & Asprillia and change the system to fit a player and riun it.