There was a lot of Internet Blog Speculation about Osili running for an At-Large seat, but I think that was coming from speculators who were basing their statements on rumors rather than reliable sources.
I think Osili has his sites set on a career in politics. It must be hard in the world of politics to go from running for a state-wide office for a full time job down to a part-time legislative office.
But in Indiana politics, it seems you need to establish a record of winning, and establish it quickly. Recent history is full of established winners and perennial candidates, and after a candidate loses, it seems like they aren't taken seriously as an office seeker anymore.
Osili saw the writing on the wall. He needs to establish a record of winning elections. And while he could've run for an At-Large seat, he would've faced stiff competition from previously announced candidates. And as Joanne Sanders demonstrated in the 2007 municipal election,the At-Large seats don't always go the way of the mayoral race.
Running for district 15 is almost a guaranteed win, and Osili will be able to spend a large amount of time campaigning for his fellow Democrats in the mayoral race (Melina Kennedy) and other council candidates in more competitive districts.
Osili has a future in Indianapolis, and maybe even state wide politics. But he needs to prove to the powers-that-be that he can be a positive and effective force. He made the right decision in running within a district rather than At-Large.