Keyword headache in google keyword tool and market samurai

A couple of months ago, i wanted to setup some sites, so done some research via google keyword tool and market samurai, and found some decent keywords. I set up a couple of sites, each of which had keywords which were said to generate at least 2000 searches per month, per keyword. At the present time, i've got the sites into the top 3 positions in google, and haven't received anywhere near the perceived traffic i thought i would have. A bit confused, i again researched these keywords in google's external tool, and can see that the search value per month has completely slumped. Each keyword is now reported to generate a little over 100 searches a month.

When i initially researched these keywords, i was aware that sometimes google's keyword tool isn't 100% accurate, so i searched for these keywords over a period of a few days to see if the data presented by google changed at all, which it didn't. It's also the reason why i used market samurai in my keyword research.

I also made sure that they keywords had a consistent search volume per month by looking at the bar chart, which they all had. There not seasonal keywords, and there's no sharp rise or fall in searches according to google's keyword tool, so what gives?

I understand that the data presented by google's tool is an estimate of what they perceive the search volume to be, going by the previous months, but to have such a large decrease in search volumes across the board is a bit disheartening. I've also just done teh same thing for some of my other sites, and their related keywords, and they have exactly the same issue. A massive decrease in the number of estimated searches for the month. I'm talking over 8000 searches a month in one case, to now less than 50. Hopefully the tool is just having a moment at the present time..........