Firstly I don't know where that information came from, but by my count Cristiano is on 59 assists for Real Madrid (in 232 apps, all comps). Özil had 72 assists in 159 games in all competitions, which is insanely good, close to an assist every other game (0.45 apg). For comparison's sake Cristiano averages 0.25 assists per game at RM, which in itself is already excellent.
Secondly, being a good passer and getting a lot of assists aren't even necessarilly linked. Strikers who aren't renowned for their passing game manage to accumulate a decent amount of assists by virtue of simply leading the line... Luca Toni has 7 assists in Serie A this season, Aritz Aduriz has 7 assists in La Liga, Giroud and Rickie Lambert both have 8 assists in the PL, etc. The vast majority of Cristiano's assists are short one-two's, flicks, pull-backs and sometimes crosses... all great skills, but not exactly proof that he could produce the same amount of chances from a deeper position (like for example Özil) which would require a different skillset altogether (vision, weight for through balls, long balls, etc.).
Cristiano is a good passer indeed, but nothing extraordinary compared to many of his contemporaries even.