Each year I start out my Liga Santander starter squad with Gaya as my left back, previous years he's been one of the first to leave the squad for a better alternative, mostly Jordi Alba or Filipe Luis. This year tho, it might take som time before I let go of him. Bought for a mere 1200 coins in the first days of FIFA early access, the value for money is insane.
He seems to be extremly well balanced in attack and defense and is well positioned at all times. 68 Physical is a understatement, he shurgs players easily off the ball, and has the pace to catch up on quicker wingers. Decent in aerial duels even tho he's somewhat short.
Well positioned, good defending and comes forward at the right times. His pace makes him come forward, but still be able to close the gaps he has left behind him. Decent crossing makes him a dangerous leftback with the new crossing system. Decent finishing when he comes forward into the box.
Stamina might be a problem if you use him as a overlapping leftback, but stamina is still decent. Can be shrugged of the ball by strong strikers like Suarez or Lukaku.