Performances, but also goals. When Marchisio was scoring goals no one said anything. Fans rate by things that are easy on the eye or easy to distinguish, put down in stats columns. When was the last time you even saw Marchisio in a goalscoring position?
When Marchisio was playing left midfield he was sacrificed for the team and completely outcast as an individual performer. To an extent he still does often play a second fiddle role to a maestro like Pirlo and a warrior like Vidal. Their skills are easy to see, more defined. Add in Pirlo taking free kicks, Vidal taking penalties. Pogba comes in and has that youthful verve, big lad with funny hair who likes a trick or two and hits a cannon shot.
What does Marchisio do in comparison? Mostly the unattractive stuff, getting the ball and linking to the strikers and his winger. Now and again he'll score a goal, get an assist or do a bit of skill to make someone look silly. That is then a 'good game' for him, when really it's just a regular game with a bit of garnish.
Still, it's been much simpler than that in the last couple of months, he just hasn't played very well and doesn't look in great shape. It is a shame he has to play the Confederations Cup, because after that he'll have a couple of weeks off then back getting hammered by Conte in training. This is why I don't think you'll see his best tempo and form until a month or so into the season.