Google keyword tool is not at all accurate in some instances. When using the exact matches count for long tail keywords, recheck the count by truncating a word from the long tail keywords to see if the count has any changes.
From experience, I got caught once by google keyword tool for a long tail exact match keyword phrase of around 30k exact matches. After building it up and ranking it to page 1, I found out that no traffic comes in. It was after I re-checked the tool and found that by truncating the keywords, the exact matches count is the SAME!