Liuzzi has two main problems:
Di Resta and his consistent underachieving.
However, its the fact that he underachieves that almost makes me want to see him in F1 still (flawed logic I know…but let me continue!). Liuzzi was mighty in the junior formulas. More so than almost any other driver on the grid. It just makes me think that his career has been mismanaged and full of mistakes. I would like to see him succeed as he has so much potential!
On the other hand though, as you say di Resta is looking mighty impressive. Perhaps Liuzzi deserves one season alongside di Resta. I personally think Sutil will leave the team this year, so that might allow it to happen