i think it's your strikers attributes they need vastly improved, you have Vydra & Fierro who are top young players and there attributes haven't really improved much,
for vydra work on his pace, Acceleration, off the ball, Composure, First touch,Passing, Positioning and creativity or maybe work him as a Poacher or Complete forward.
for Fierro i would highly recommend getting him tutored by someone with high determination because on my he's 18-19 years old with an determination attribute on 18 and his attributes are increasing very fast but again train the attributes the same as Vydra he will when trained properly become the best Poacher & Complete forward in the game