Sadly, this is not always the case.  I know many 
times I've been late to a dealer update only to 
see what I wanted to order on eBay within the 
next week going much higher.

However, I know the phenomenon you are speaking 
of as well.  There might be many reasons for it.  
For one, many people might not be checking eBay 
because it's annoying to browse (especially in 
comparison to something with free and more 
plentiful thumbnails/gallery).  Also, they may be 
leaving the auctions til the last minute and then 
forgetting/sleeping through/missing (this happens 
to me a lot).  

Another reason is the dealer-update-rush.  When 
there's an update, people have to quickly come up 
with a yes or no answer, they may side with 'yes' 
so they won't regret it later.  When it's on eBay 
they have more time to think about it and maybe 
decide 'no' or have something else come up (like 
something they said 'yes' to at an update rush... 
taking all their money away).  I try to be 'good' 
with my cel triage but it's so much easier to be 
poor.

Plus, it's just a bad season to sell right now it 
seems.  I know there are a ton of things I would 
like to buy but there are cons, other things I 
bought, other stuff coming up for sale.  Things 
that went a month ago on a dealer's site might 
not fetch the same price right now just because 
of the selling season.

These are just a few reasons I've come up with.  
I'm sure there are more.

Keys