Question: why does this site rank higher for a keyword

I'm trying to figure out the abiguity in regards to a certain keyword (3 letters, 1,870,000 results)

The site that ranks in #1 position has the following stats:

Site A: #1
Inlinks: 363 (Siteexplorer)
PR: 2
Indexed pages: 136
Age of domain 2007

Site B: My Site

Inlinks: 927
PR: 3
Indexed pages: 3k
Age of domain: 2009

The only factor that I see is that Site A targets a micro niche, where as only a category of my site targets that niche. But on a high level my site targets a niche higher

(ex: i'm targeting the niche 'clothes' of which there is a category called 'skirts' where as whole of Site A targets 'skirts') Could this be a reason?

Creating a new domain/site isn't quite the way to go. So what measures can be taken in order to get my category to outbeat Site A?

• Presently, i'm using scrapebox with the '3 letter keyword' as the name and blasting comments.
• My site has links coming in from Wikipedia (I know i know, there is no link juice being passed)
• I have my articles published in the same directories as Site A

What I do notice a big difference is links from squidoo.. But is squidoo only the real big factor in the rankings?

first - quality>quantity (squidoo is lot heavier juice than spammed blogs)
secondly - targeted niche>global niche+targeted niche

also some would say domain age might have a part in this situation

Yup I agree domain age could also be a factor, and on page seo maybe? Keyword density?