Gary Welsh of Advance Indiana has a nice article on the subject. He mentions that this is not the first time that attorneys have rejected a big firm attorney and cites the case in which William Winningham defeated Carroll and several other candidates for a 3-year term on the Commission in 2010. However, that was a race that featured two big firm candidates. Here the big downtown Indy firms had consolidated forces behind Carroll. A third candidate, who might have drawn votes from Carroll, was apparently talked into dropping out of the race.
Here is why I say the result is so surprising. Carroll began the race with a solid base of voters from the downtown law firms. Christie, on the other hand, began the race with no such advantage. He had to earn every one of his votes, informing smaller firm attorneys about the issues. It's as if Carroll and Christie ran a 100 yard dash and Carroll was allowed to start on the 50 yard line. Yet Christie won the race by a good margin.
While Christie proved to be a strong candidate, it is apparent that attorneys were also voting en masse against more large firm (in particular, Barnes & Thornburg) control of the Indiana judicial apparatus.
Personally I think it was a political mistake for Carroll to send a mailer out listing all her supporters, virtually every politically-connected, law partner in Indianapolis. People outside of those firms do not look at those folks with respect for the position they achieved. Rather they see their positions in the legal profession as gained through a lot of political influence and being in the right place at the right time.