You've gotta be kidding me.
A player is not measured solely in statistics, particularly somebody who plays Claudio's position (DM), and who was also hurt early in the year.
I never said the player has been spectacular this season -- nobody on the team has been, in case you haven't been watching. Marchisio is a huge stabilizing force in the lineup, he's a huge part of the team -- and if you can't simply see that, if it's not apparent to you that we're a much better team with him in the lineup than without, I don't know what else to say. No point writing an essay on his attributes, as I used to do in the "Casper" days.
You don't think Marchisio could have helped at all against Roma, Napoli, or Fiorentina? Early in the season, during a massive injury crisis, with the team out of sorts? Seriously? Did you see Hernanes get utterly annihilated against Napoli?
My "standard"? Asa, Neto, Rubinho? That's some stronk logic there, fella.