I think there's more to players than just ability. Basically all of the all time greats were the most influential players at their club. You simply can't say the same for Iniesta right now. On ability alone, I think he's up there, without a doubt. Not sure that's enough, at least not for me. Playmaking is more than just assisting in stlye, imo. We don't know what kind of influence Zidane would have had, had he played all his career with maybe the best of all time. That's pure speculation. I rate Xavi's influence in 2008/09-2010/11 way higher than Iniesta's now, for example.
By the way, Zidane faced for sure tougher defensive formations than Iniesta in the league, especially in Italy. Juve scored on average 53.4 goals a season during the 5 years Zidane played in Italy. 14 assists when your team scored about 50 goals sounds pretty great to me, 12 assists when you're playing with the greatest goalscorer of all time, breaking every record imaginable and your team already scoring 72 goals in 22 games isn't as impressive after all, don't you think.
I asked for the last years, not only half a season.
Özil:
2010/11 19 assists in 36 games
2011/12 20 assists in 35 games
2012/13 8 assists in 21 games
Iniesta:
2010/11 4 assists in 34 games
2011/12 11 assists in 28 games
2012/13 12 assists in 16 games
stats from transfermarkt.
Now, I think saying he stands alone is a bit over the top. He had a better season so far than Özil, without a doubt. Probably the way the team is set up now, increases his influence in the final third. I don't think he's a totally different player now than in 2010/11. Oh and I'm pretty sure the german league is missing in your assist table. Müller has 10 assists in 19 games, for example, some have 9 assists with less games than the players in your list.