I think Brohm has kept Purdue extremely competitive in his first two years in almost every game. In addition to the 6-6 record in both seasons, the largest loss margins were Michigan (lost 28-10 in 2017) and Minnesota (41-10 in 2018). Here are the other loss margins:
2017:
Louisville - 7 points
Wisconsin - 8 points
Rutgers - 2 points
Nebraska - 1 point
Northwestern - 10 points
2018:
Northwestern - 4 points
Eastern Michigan - 1 point
Missouri - 3 points
Michigan State - 10 points
Wisconsin - 3 points
So while they've played down to some inferior opponents, they've also played up and beaten some quality ones and in many of their games it wasn't even close. One could argue that their only really bad loss against Minnesota this year was a fluke possibly due to speculation he would be leaving.
I'll be worried about Purdue as long as he's there.
You don’t see inconsistency in those results? I watched several of their games this year and saw undisciplined up and down play all season. I think that is a reflection on the head coach. I am no fan of PJ Fleck as a person but I was more impressed with the improvement and the job he did with that Minnesota team with a freshman QB than I was with what Brohm did at Purdue this year. It would have been better for NU if Brohm had left but I still won’t lose any sleep over Purdue.