How can the same key term change positioning seasonally impacting some companies and not others?

[SSRMarketing]

The company I do SEO work for is a vacation rental company.  Through research, reports, and crunching numbers I've discovered the seasonality of the buiness (when what we do is a popular search and when it is not).

The problem I've encountered is that our average position for google seems to follow this exact same seasonality, but only for us.  What I mean is, as the season for looking up vacation rentals in our area fades away we take a serious nose dive in our positioning, yet when the season comes back we once again are first page.  The other interesting fact is this isn't happening to the other companies who are in the same area.

How can the same key term change positioning seasonally like that and impact some companies and not others?  Can you give me some insights into where to at least look or pursue?  I should have started with you guys, but I had so far spent 4 months trying to get answers and so far I've come up with nothing more than guesses and frustration.  Please help me.

[SEOAndy]

I would suggest the kind of linking and marketing you are doing away from your seasonal times. If you are still link building and trying to push rankings during your 'off peak' season I don't see why you should nosedive.

Look at ways in which you can use the off peak to really push your marketing forward. For example creating content and just generally being active throughout the year and still trying to build your back link portfolio.

Obviously you want to market toward the time when you get the most business, but 'off season' can be just as important.

It might be that more people are linking to you and talking about you during your seasonal time and Google is seeing this and ranking you accordingly, but when that stuff dies away and not much more comes through your competitors begin to rank above you due to the kind of SEM they are doing.

Hope that helps in some way. Any more information could help give a better analysis.