(I typed this over lunch, so please ignore typos, poor grammar, etc)
A. Case History
Purdue's season started on a high note, and went downhill with each successive game. A win against Iowa was followed by a win against Illinois that was much closer than it needed to be due to the defense being unable to stop Illinois' third string QB. Not a great sign. Those two wins were followed by a close loss to Northwestern, and defensive and special teams meltdowns that led to losing four in a row and giving up over 35 points per game against Minnesota, Rutgers, and Nebraska.
The season couldn't have ended on a worse note. A season that had started out with promise ended with embarrassing losses, and (some) players who looked like they didn't want to be there. Bob Diaco was fired, and the narrative of dysfunction, stagnation, or even decline from the lofty heights of barely making a bowl was set.
B. Opening Statement
I would first like to submit into evidence a few undisputed facts. The 2020 Purdue team was ranked higher in S&P+, 42nd, than any previous Brohm team. That is higher than 2017 and 2018--ranked 48th and 44th respectively--and significantly better than the 64th ranked 2019 team. Before the 2020 season they, for some unknown reason, hired Bob Diaco to replace Nick Nolt as D coordinator. Their defense improved from 82nd in adjusted defensive efficiency in 2019 to 60th last year. Bob Diaco was fired this offseason and replaced by Brad Lambert. In red zone efficiency Purdue finished 2nd, 3rd, and 2nd over Brohm's first three years. They were 108th in the country, and, I believe, 12th in the Big Ten, last year. Purdue returns a good amount of production on both offense and defense. Finally Purdue S&P+ rank was 36th on offense and 60th on Defense. For other middle table big ten teams, those S&P+ numbers are NW 30th (92nd Off, 3rd Def), Nebraska 32nd (35th Off, 38th Def), and Minnesota 34th (18th Off, 64th Def).
With that evidence in mind, I believe the evidence shows that Purdue is the least likely of the above mid-table Big Ten West teams to regress, and the most likely to make the significant jump to challenge Iowa and Wisconsin at the top of the division. To start, the teams listed above, like Purdue, all have significant issues entering the 2021 seasons. For NW, they had a bad offense and must replace basically all skill positions players and most of the defense. For Nebraska I direct you to their game on Saturday. For Minnesota, its the loss of Bateman, and a defense that struggled mightily in 2020. For Purdue, the defense in 2020 was obviously a problem that got worse as the season went on, and that was in addition to their extreme inefficiency in the red zone. Finally, Minnesota, Nebraska, and Purdue all had special teams units ranked in the 100's. Not great.
To take the chance of regression first. The case for regression at Nebraska is clear, especially after their loss to the Illini on Saturday. Could Nebraska pull out this season? Sure, but the special teams mistakes, penalties, lack of playmakers (other than Martinez on occasion), and poor coaching show how things could (and maybe already are) going wrong. The case for regression at Northwestern, while far from assured, is clear as well. When you are mediocre on offense and rely on one of the best defenses in the country to win close games, regression by one or both units could lead to losses piling up. And it's hard to imagine their defense maintaining the standard they set last year after losing so many key contributors. Add in that the offense lost the top four WR's and top three RB's in terms of production, in addition to replacing Ramsey with Hunter Johnson, and there is at least a reasonable chance at regression on offense. On the other hand Purdue and Minnesota, who both return most of their production, have a significantly lower chances of regression this year.
The Boilers also have a better chance to make a significant jump on offense and/or defense in 2021 than either Northwestern or Minnesota (Nebraska goes without saying at this point). To state the obvious, Northwestern's defense is unlikely to be 3rd in the country after losing so many key players, and even if the replacements are better than expected, they just don't have any real space to move up. Could Northwestern's offense be better than their 92nd rank last year? Sure. Does Hunter Johnson with a new back field, and throwing to a bunch of new WR's sound like a recipe for significant improvement on offense? Not really.
Now, Minnesota had a very good offense last year, and likely will this year as well, but is it primed to jump from 18th into the top ten? The run game will be very good to great, like last year, but the passing game is unlikely to improve significantly after the departure of Bateman. On defense there is certainly room for improvement from 64th, but you are running it back with the same players and the same scheme. I would bet on steady incremental improvement, rather than a major leap. To put it simply, I don't know that, other than Mafe, I see a player as talented as any of the draft picks (or a few others) from their 2019 team.
Which brings us to Purdue. To start, Brohm seems to have a plan to fix the red zone issues Purdue had last year. With that said, if you look at his record from WKU to his first three seasons at Purdue, the 2020 season was a significant aberration--one possibly caused in part by luck and a small sample size. Even 2019, when Purdue was delimitated by injuries, had freshman score 16 TD's in a row, and had an even worse run game than last year, they still finished 2nd in the Big Ten. To state it plainly, I would be surprised if Purdue is in the bottom half of the Big Ten in red zone efficiency this year.
But defense is where I see the best chance of major improvement. To see why just look at the undisputed facts I listed above. The Purdue defense hired Bob Diaco. And Purdue's defense improved from 2019. I will not insult the readers intelligence by suggesting that Bob Diaco was the reason Purdue's defense improved by over 20 points last year. Rather, the defense improved because the freshman and RS freshman from Brohm's first two classes were thrown to the wolves due to the injuries that ravaged Purdue in 2019. Karlaftis was already a starter as a true freshman, but Cam Allen and Jalen Graham also ended up starting as true freshman, and RS freshman/true sophomores Jaylen Alexander, Lawrence Johnson, Branson Deen, Corey Trice, and Jack Sullivan to name a few all started or contributed significant minutes. Those players were able to improve defensive efficiency in 2020 despite Diaco showing up, alienating staff and players, and implementing a scheme seemingly designed to bury the one strength the Purdue defense had.
In 2020 Purdue's defense has as much talent, and as much depth, as it has ever had under Brohm. It also has a new Coordinator who has installed a scheme that caters to his players strengths. Purdue's last good defense, the 2017 unit ranked 32nd in S&P+ (which had improved from 102nd the year prior), employed the same type of aggressive scheme to stop the run and put pressure on the QB during passing downs. Except this year, instead of a bunch of Hazell recruits* we have Brohm's first top 25 class coming into their Junior/RS sophomore year. If any of the units discussed above is going to have a break out year, I would put my money on the Purdue defense.
All of that to say, I think there is a good argument that of the mid table B1G West teams Purdue is poised to improve the most, and, coupled with their similar S&P+ ranks and the fact they basically all played each other to one score games last year, make the jump to challenge Wisconsin and Iowa for the Big Ten West.
*There were actually some really good players on that D recruited by Hazell like Bentley and Bailey, but the average talent level was not great.
C. Emotional Plea
Instead of an emotional plea, I would ask people to try and set aside the narratives and emotions caused by the way last year ended. To do that, I would ask you to imagine an alternate universe where Purdue isn't called for offensive PI at the end of the Minnesota game. If they won that game they would have moved to 3-1 overall. In that alternative timeline, we can even stipulate the special teams miscues and general lackadaisical play that cost Purdue games against Nebraska and Rutgers still happen, leading them to finish 3-3 and tied with Wisconsin for third in the Big Ten West.*
The narrative around Purdue this season--stagnation and possibly decline--is driven in large part because Purdue followed up a 4-8 injury plagued 2019, with a (somewhat less injury plagued) 2-4 record in 2020. That framing leads fans and commentators to focused on the negatives--the problems on D from last year, the third D coordinator in three years, etc. While a change in framing or narrative caused by improvement in the win column (even if all other plays stay the same) pushes people to focus, or at least notice, the positives heading into 2021. The story becomes how a young Purdue team bounced back after an injury plagued 2019, and is potentially poised for a significant jump as Lambert improves the D, and Brohm's talented recruiting classes enter their second and third year in the program.
In this alternate universe, the problems with Purdue I identified above are still present (as are the solutions), but because Purdue improved in both advanced metrics and record, the narrative changes from stagnation or decline to one of continued improvement.
So, the plea I would make to you is this. Don't let a blown call overly influence how you think about Purdue's chance of success this year.
*Unrelated hot take. That PI call was the best thing that could have happened to Purdue. If they finish 3-3, and improve by 20 points in defensive efficiency, does Bob Diaco get fired? Probably not, though he and Brohm really didn't seem to get along. If Purdue is saddled with Diaco for the next few years, is there any chance Purdue doesn't continue to struggle on D?
Purdue has a very difficult schedule, and I could see anything from 4-8 to 8-4 being reasonably on the table. But I think Purdue improves. I think the red zone efficiency goes back to being in the top five, if not higher. I think the run game will be marginally better, though Purdue will still rely on their passing game. I think the defense will jump into at least the 40's in defensive efficiency. And I think Marty Biagi will get the special teams sorted out after trying to install his scheme during covid. Put that all together, and I think Purdue will be roughly a .500 team against this schedule, if they get a few breaks they could win 7, injuries or bad luck/call, and they might win just 5. But I'm an optimist, so I'll say 7-5.