Wanted to put input, so forgive me.
Look I do believe Marchisio I a good player. A very good player. The only thing i have to say to his critics is this.
Prior to 2008, Would anyone would have consider Xavi an top 10 world class midfield. Very few would. Or a better case. Before last season, Bastian Schweinsteiger was a good player. Didn't Seem( On my part) to have the qualities of good winger outside of a good cross. Under Van Gaal however, He saw his strengths, move him to CM, and played him towards his advantage. Now he's considered one of the best midfield not named Xavi.
I'm not saying that he's the next Xavi. No, not at all. All I'm trying to imply is that we have to find a manager that know Marchi's Strengths, and molded him into a great player. Remember, even at 25, a player still grows. His Peak isn't until 27-28.
Just my opinion. Hopeful, i was clear, and not trolling.