The choice isn't too surprising. Oxley is young, well-spoken and his district covers a large area of Southern Indiana, where Thompson isn't as strong.
In the Democratic primary, Thompson won narrowly with a strong showing in Northern Indiana, where she previously served as a congresswoman and now lives on a farm in Marshall County.
Her primary opponent, Jim Schellinger, an Indianapolis architect, took the south, winning handily in a number of counties along the Ohio River.
So the choice of Oxley makes sense geographically. His district is huge, with parts or all of eight counties, running from Perry County on the west to Scott County on the east. That makes him well-known among many Southern Indiana voters and local politicians.
I really don't know enough about Oxley at this point to know all the pluses and minuses he brings to the Democratic ticket. Based upon the reaction of some Democratic bloggers, there doesn't seem to be a lot of excitement about his addition to the ticket.