He may have potential but in his position we need the finished article. As you say he isn't close to that at the moment. If we are going to spend the reported amount of money Soton are asking best to look elsewhere.
But , as we have seen , recruiting the ‘finished article ‘ is difficult for a mid table team with no European football to offer and a recent history of relegation struggles.
We either settle for players of a lower quality which will not improve us significantly, or take a risk like this , which is a calculated risk considering how highly he is rated by people who know the game.
One final point , having researched his performances last season , I would say he is already a capable player more than able to hold his place in our side.