Gag can only win ball if it comes right at him. He stays close to the central and hardly roams around, yet if the opponent is only a few meters away, he could never chase/reach them. Look like me chasing Usain Bolt. He can still be effective if he has great anticipation to be in the right place like Cambiasso but he doesn't. He's not really physical superior either, won only 50% of duels. How can he win the ball with such limitations?
How is he worse than Valero and Vecino? Look at some stats sites. Stats hardly lie especially when it comes to central midfielders. All stats sites show Gag is worse than Vecino and Valero. I don't need them to know which players are good or bad, yet it's the easiest way to show you. For example,
http://www.squawka.com/players/roberto-gagliardini/stats
Gag's overall score: 22 games, 161 points
Vecino: 23 games, 307 points
Valero: 25 games, 395 points
The difference is too obvious.
All of our midfielders are "support" type. They can't be the main midfielders, need to play alongside midfielders that are better at either defending or attacking. We need a healthy Rafinha and need to bring Torreira in. Valero and Vecino can be decent with support role alongside them.