I cannot tell you the passing stats for all the players at the time of Xavi's substitution...
I can. You can limit stats by time at Squawka.com (using the sliders).
First 60 Minutes (Xavi off at 61 minutes):
Xavi 49/56 88%
Pedro 25/31 81%
Iniesta 54/60 90%
Sanchez 15/21 71%
Messi 27/32 84%
Pinto 2/4 50%
Mascherano 36/37 97%
Bartra 33/37 89%
Busquets 51/52 98%
Adriano 42/48 88%
Alves 66/71 93%
Number of through-balls attempted by the ENTIRE team in first 60 minutes:
1 (Messi, 42 min). Number completed:
0.
Number of key passes first 60 minutes: 8 (2 each by Pedro, Alves, Iniesta, and Messi)
So Xavi about the same as Iniesta for time on. And the only reason Xavi has no through-balls is the same reason no one else on Barça has any: there weren't any to be had.
Number of through-balls attempted by the ENTIRE team in LAST 30 minutes: 1 (Busquets, 83 min). Number completed: 1.
Number of key passes LAST 30 minutes: 5 (2 Messi, 1 Busquets, 1 Alves, 1 Cesc)