That has way more to do with the team around him and the play calling than him.
I'm sure that's the easy way to explain it. Not sure if that's the right way or not.
Last series of downs on each possession against Purdue:
From the Purdue 18 - run for no gain, incomplete pass, complete pass for 2 yards (holding penalty), run for 1, FG
From the NU 28 - run for -1, false start, pass for 7, sacked for -2, punt
From the NU 17 - incomplete pass, run for 4, incomplete pass
From the NU 36 - incomplete pass, incomplete pass, pass for 9, punt
From the Purdue 4 - run for 0, incomplete pass, incomplete pass, FG
From the Purdue 48 - pass for 4, run for 4 (holding penalty), pass for 8, incomplete pass
From the Purdue 25 - run for 1, pass for 6, incomplete pass, FG
From the Purdue 9 - run for 4, run for 3, incomplete pass, FG
From the Purdue 27 - passing TD
From the NU 48 - run for 1, incomplete pass, sack, punt
From the Purdue 19 - run for 0, run for 4, incomplete pass, incomplete pass
From the Purdue 19 - pass for 6, incomplete pass, TD pass
So Lee's stats on the drives where we didn't score a TD were 6/17 (35.3%) for 36 yards, 2.1 yards per attempt, 2 sacks for -14 yards, 22 yards net on 19 passing plays. So I think it's fair to say he contributed his share to the struggles.