From the OS:
Naismith played two thirds the amount of minutes played by Barkley (Naismith 1,820 to Barkley's 2,616).
When you look at the stats from the OS it reveals in terms of total defensive category/work (clearances/blocks/interceptions):
Naismith 30 C/B/I
Barkley 42 C/B/I
So that's pretty much evening out given time on the pitch.
Successful passing is where it really shows in Barkley's favour:
Naismith 430
Barkley 1,052
Naismith may be only two thirds of the time on the pitch than Barkley last season but his successful passes per minute on the pitch are barely two thirds that of Barkley's.
Naismith had it over Barkley in terms of goals - 9 goals compared to 6 for Barkley.
What you're looking for from an advanced midfield player is a good mix of defensive duties, passing and attacking play. Obviously, Naismith is really an attacker without pace or height who's being utilised to good effect of late as an advanced midfielder (plays in the hole actually) and that reflects his goalscoring. But that role (as well as defensive duty and goals/shots on target) requires a player above all to be a pivot, and that's where Barkley is head and shoulders above Naismith. As said, Naismith is basically an adapted attacker doing a job in behind the attacker, he cant do that creative work someone like Barkley does.
