You've got an inexperienced O line. It is critical you have a QB who has accuracy and can stretch the field, even a little bit.
Think about every pass play called for Leonard except for the stupid long INT. Every one is a short out route, and the safety valve is about 5 yards downfield.
Leonard's skill set only works if you have an extremely strong running game, which ND doesn't have right now. Yes, I know the avg. YPC is over 6 but there have been several long runs that skews that.
If the offense bogs down again against Purdue, hopefully Freeman and Denbrock do the right thing and admit the obvious.