If Lucas Moura hasn't gone the way of most recent Brazilians (in that they peak at 25), he will be a tremendous signing for them.
For all their skill and ability, Spurs have missed a player who can skip 2 or 3 players easily. Eriksen, Kane, Alli are outstandingly efficient players who lack dribbling ability. Son gives them a bit of dribbling and skill, but he lacks the power of a Hazard/Mane/Sanchez. This Moura kid has it.. or at least had it.
Hopefully Sunday is too early for him, given that he hasn't played consistently for some time now.