Do some math, then post. Considering the size of Coakley's initial lead, obviously many of those that switched will fall in this 2/3. Like I said, owned.
Coakley was originally 60-40. Brown won 52-47. Roughly 2.2 million people voted for either one, it total. Brown ended up with about 1.1 million votes. Had he only gotten 40%, like the original polls, he would have ended up with about 900,000 votes. (This would be his base number) 2/3 of his actual voters is 733,000. You fail.
http://www.boston.com/news/local/massachusetts/articles/2010/01/10/senate_poll_coakley_up_15_points/ She was up 50-35 with 7% undecided. Including the undecideds as they were leaning at the time, she was up 53-36. Yes, Kennedy was at ~9%. He finished with 52% of the vote, so 17% switched, or 1 in 6. 17% of the ~2.2M votes is ~375K voters Considering he got 1.17M votes, 1/3 of his voters were not with him the whole time and clearly that 1/3 switched for the reasons BB posted: "their vote was intended partly to show opposition to the Democratic agenda in Washington, including the health care overhaul."