My initial reaction, too, was that this is likely human error. I had always wondered about the subjectivity involved in that gray area between line drives and flyballs (how many times do play by play guys refer to humpback liners?). I hadn’t thought about the dividing line between grounders and liners, which is brought up also. Someone suggests that more balls in the outfield gaps are coded line drive, which would be an interesting bias.

I wonder how many people are making these determinations at MMP?