As Kieran pointed out you have quite a bit of duplicate cotent, thus I expect you have been pushed right back in the SERPs.
Also the lack of links to your site could be an issue as your site currently carries very little authority, especially when compared to your competitors. But this is a good thing (better to work with no links than hudnreds of bad links!).
I like the site, its nice a clean., but one thing i did notice was the lack of social integration. I recommend you incorporate some kind of social sharing (i did recently and its definitley helped my SERPs).
You could also create some social accounts on twitter/facebook etc (don't know if you already have) and start talking to your potential customers (theres always alot of footy banter!)
Consider writing some original articles on Arsenal and getting them posted on other fans blogs (with a link back to your site of course).
Your niche is great for the amount of people whom you can engage socially, on twitter, blogs, facebook etc...mine is a real nightmare (coat hangers, who wants to talk about them?). Use the social side of things to your MASSIVE advantage. 