I'll do a text version of GL66 stats, if you want. But I think, it will be better take there cards or discuss some areas.
So, for the GL66 stats:
Agility: I'd leave it as 79
, he is no lesser agiler than Gallas and I think it fits him well, in game.
Aggression: I think that 68 is a bit low. I know he doesn't attack very often, but maybe something like 70 would be better for him. 78 is definitely very much, he really isn't a DMF, who loves to go forward. Mikel is ATT 70/AGG 70, so this change can be made IMO. About mentality, I'm pretty sure he could be in middle 80's. He is very hardworking player, he very hardly gives up of walks on the pitch. Technique is good at GL66 stats, dribbling, passing. Yeah, I like them!
About Player Index:P
04 - Anchor Man (65% sure)P
14 - Enforcer (30% sure)S
09 - Covering (90% sure)
I don't say he deserves them, I want to discuss about them. Anchor Man could be, but then a raise in aggression could be maybe even bigger, Enforcer.. not sure, rather I'd say he doesn't need it, he takes everything by his great positioning, not as "aggressive" as Gattuso for example IMO. Covering is needed, I think I'm 90% sure about it, he is a "saver" many times and he proved to deserves this card.
I know that i don't know anything.