Aberdeen's entry standards, in terms of average UCAS points, is about 370 or so. Given that CCC is 240 points, you can see that it's actually significantly higher than that. A point that is almost always forgotten about on TSR, is that most Scottish students have less UCAS points than their English counterparts.
A Scot with AAAAA at highers gets 360 points for this, 3% of Scots get this grade or better.
An English/Welsh/N.Ire student with AAA at A2 also gets 360 points, 11% of students get this or better.
Ergo, to be in the best 10% of Scots, you need substantially less than AAAAA, but as a result you'll have less points than someone in the top 10% elsewhere in the UK. Students there aren't less intelligent- it's more about the exam system. The result is places like Aberdeen with 80% Scottish students or Glasgow with 70%, are going to have marginally lower entry than an English university, or even a Scottish university like St Andrews with only one in three students coming from Scotland.
You will find lots of very good students at Aberdeen, especially Scots on the four year degree. The different exam system and the lack of demand outside of Scotland means they have lower offers, but first year of a Scottish university can be repetitive for those who've did well in English exams, since their degrees are three years. I really wouldn't worry about CCC- that wouldn't have put me off going (I didn't, but my uncle and aunt did in the mid-90s), and it's a nice place. Having lower entry is one of the criteria that league tables are built on, so that handicaps Aberdeen to an extent as well. If you consider the overwhelming majority of people at certain Scottish universities, of which Aberdeen probably warrant inclusion, are in the top 5% of their class- then if you were to compare it with an English university with the same sort of applicant pool- probably somewhere like UCL, then you'd find a much higher average UCAS score, which partly helps a better ranking- or again, a Scottish one with not many Scottish students (Edinburgh and St Andrews, take note).
Ultimately, tables are meaningless, but it's hard to convince people of that, especially when they're at school-leaver age. Employers don't take much notice though, luckily.