... in all 3 macthes he has been decisive.
No-one could argue with that.
However, it doesn't mean that people aren't right in saying that, in many regards, Juve don't function as well as a team with Pogba playing instead of Marchisio.
Now, it doesn't matter much that Pogba playing causes certain issues when he is consistently proving to be decisive in key incidents in matches.
I would also suggest that of the major moments Pogba has been involved in in the three games, his pass through to Vidal to set up the first goal against Lazio is the only one I couldn't envisage Marchisio doing.
In fact, Pogba's role in the goal against Sampdoria was exactly the sort of run that Marchisio has made in the last few seasons, so I would say that there would have been a very good chance that Juve would have scored that goal whether it was Pogba or Marchisio who was playing.