OSU Defense Pre and Post-Bosa

Submitted by Unicycle Firefly on November 21st, 2018 at 2:12 AM

I saw this question posed in an earlier board post, so I figured I’d do a little deep-dive to see what the impact has been of Nick Bosa being out of the OSU lineup for the past 8 games, and what that might mean for Michigan. 

Let’s go ahead and start with some basic charts.  First, OSU’s defensive performance during its first three games, when Bosa played, broken down by rushing, passing, and total defense:

Chart 1.png

Now, let’s take a look at OSU’s defensive performance post-Bosa:

Chart 2.png

Some key takeaways after a quick review and comparison of the charts:


·         OSU’s completion percentage allowed is slightly worse, but by a negligible margin.  Passing TD’s allowed are basically the same.

·         OSU is giving up almost 67 more passing yards per game in Bosa’s absence.  This could be a function of opposing QB’s being able to hang in the pocket longer and throw farther downfield with a hampered OSU pass rush.


·         Surprisingly, almost no drop-off since Bosa’s departure.  OSU is giving up about 8 more yards per game, while yards per rush and TD’s are almost unchanged.

                                                                  Total Defense

·         Taken in the aggregate, the news looks a little better here if you squint when looking at the numbers.  OSU is giving up around 74 more yards per game, which is…ok, but nothing to get excited about.  Touchdowns per game are almost the same.

                                                              Red Zone Defense

Ok, so maybe Bosa’s departure hasn’t had a major impact at first glance, but what happens when we narrow our focus to OSU’s red zone defense?  Charts?  Charts:


                                 OSU with-Bosa Red Zone Defense

Chart 3.png


                                 OSU Post-Bosa Red Zone Defense

Chart 4.png

Now we might be getting somewhere.  Caveats about different sample sizes apply here, but a few things really jump out when comparing the numbers:

1.       OSU opponents are getting to the red zone almost twice as often post-Bosa.

2.       OSU is giving up twice as many red zone scores.

3.       Offenses are converting in the red zone at a rate almost 20 percent higher with Bosa gone.

4.       Teams have doubled their number of red zone TD’s post-Bosa.

Now, these numbers seem encouraging, but is this a case of correlation not necessarily equaling causation?  I decided to sit down and eat some tape to find out.  I basically just watched every red zone touchdown given up by OSU this season (by far the most enjoyable part of writing this diary), to see which touchdown plays were run to Bosa’s side of the field.  This was relatively simple, since Bosa lined up on the same side of the line on every snap.  I counted touchdown plays that were either run directly to Bosa’s side, or plays where Bosa/his replacement pinched down and/or were blocked right out of the play.

So, what did the tape show?

Bosa on the field Red Zone TD’s

Chart 5.png


Bosa Not on the field Red Zone TD’s

Chart 6.png

Note: Oregon State scored a Bosa-side TD when he was not on the field,
and TCU scored a Bosa-side TD after his injury

Now we’re really starting to see the potential impact of Bosa not being on the field.  When he was out there, OSU’s opponents managed one touchdown to his side of the line in the red zone.  In his absence, teams are picking on that side of OSU’s line in the red zone with increasing success. 

What’s particularly noteworthy and Michigan-relevant here is the method by which Nebraska was able to target Bosa’s vacated spot on the line.  Scott Frost utilized the read-option to lethal effect when the Huskers got near the end zone.  Their second red zone TD was a textbook read-option that just completely froze Bosa’s replacement: 

RO 1.png

Martinez kept and scored, but the defensive end was so flat-footed and hesitant that either decision would have put the ball in the end zone.

Nebraska’s next red zone touchdown was yet another read-option-looking play that Martinez kept and ran right into the hole where Bosa’s replacement (circled) was getting blown out of the play:

RO 2.png


To my amateur eye, there certainly seems to be some correlation between Bosa’s departure and a decreased defensive performance on OSU’s part, especially in the red zone.  My rudimentary statistical analysis doesn’t really prove a rock-solid connection between the two, but there are some strong indicators.

As far as this Saturday, we can all cackle with knowing glee if Shea Patterson is performing crisp read-options in the red zone, right toward that glaring Bosa-sized hole in the Ohio State defensive line.












November 21st, 2018 at 3:54 AM ^

Wow, this is some nice work!  Must have taken some time to put together.  A shame your graphs are not showing up at least for me (Windows/Chrome).

To my untrained eye there is something here. And hopefully our staff has also noticed and will take advantage as you suggested.

Blue Dispatch

November 21st, 2018 at 7:33 AM ^

You've done a great job showing the impact of a  post-Bosa defense. Another impact off the field is a former team captain quitting the team and school, basically giving the finger to the whole program and fan base.


November 21st, 2018 at 9:15 AM ^

I thought the same thing earlier on.  But at this point, later in the season, don't you think that the focus is on the game at hand?  Besides, they can use the "screw that idiot for leaving, we're going to show the world we can do it without him" type of Dantonio disrespect meme as a motivator.

Ecky Pting

November 21st, 2018 at 10:15 AM ^

Very, very interesting indeed!

I'm curious about the implicit shift in opponent TD from non-Red Zone to Red Zone. It suggests that OSU has improved its ability to contain explosive plays (more emphasis on LB's and DB's) to cover for it's diminished pass rush. As the active field of play becomes compressed in the Red Zone, the weakness in DL play you've hit on becomes more exposed...? This combined with the already well-established under-performing OSU LB core makes for some very bloody water, and loud licking of chops by the M offense.

On the Meta side: Sorry to see your charts didn't make it in. I'm guess this was your first diary in the MGoBlog 2.0 era. Been there, done that - I feel your pain!


November 21st, 2018 at 10:35 AM ^

This is great stuff, thank you.  I'd only quibble with your conclusion that 74 yards isn't anything to get excited about.  That's actually pretty massive: based on just the median yards per game (408), that's an 18% increase in yards allowed.  If you look at the passing effect alone, where it seems Bosa would really have an effect, it's even more stark: 67 yards on the median passing offense of 233 yards per game is a 29% increase.  That's massive. 

Numbers go up or down depending on where those 8 opponents fall on the distribution.  But to my mind this seems significant.  Small sample size though. 

Ghost of Fritz…

November 21st, 2018 at 10:39 AM ^

This is a great post. Could be partly that with Bosa, opposing OCs had to alter their play selection to just avoid having to run at Bosa, thus making OSU defenders not have to really thinking about defending the entire field.  Sort of like how opposing OCs reluctance to throw at David Long makes the rest of the Michigan D better.

Related question:  Anyone know what kind of D they run in the backfield?  Cover 2?  Or something else?  Seems like IU had success limiting M's long runs by playing cover 2.  Is cover 2 something OSU does?  Seems like it might be a good idea against M.  But they probably can't try to do it if they have never really done it all year. 

Cover 2 could work for OSU against Michigan just like it worked for IU--it would eliminate long gain runs and make M earn several first downs to get into the red zone.  Bend, but make M methodically march into the red  zone (and then hope M continues to be mediocre once in the red zone). 

OSU can move the ball and score, so they don't have to play D the way MSU has to play D against Michigan.  OSU could win a game where M gets a lot of yards between the 20s, but mostly settles for FGs in the red zone.  MSU really can't win that kind of game. 


November 21st, 2018 at 11:17 AM ^

I think they run the Cover 4 that's now the rage everywhere, but we'll find out in Seth's Fee Fi Foe Film. 

It seems everything OSU does to mitigate something opens up another problem somewhere else.  It's an aggressive scheme in which they continually get caught.  Bill Connelly's article said they're good on most downs, but then get killed for big plays. 

They're aggressive, but everyone has been able to scheme them.  So they fix what happened last week, but the next team finds something new.  They don't have the killer athletes to make them right anymore. 

Ghost of Fritz…

November 21st, 2018 at 11:39 AM ^

Just read an OSU site analysis that sort of concluded that they have a scheme problem.  They don't have the level of guys this year at LB and DB that they have previously had that are necessary to make the scheme work. 

It made me think of how D. Brown's scheme would work (or not work so well) without a D. Long level CB, a D. Bush level LB, etc.  

Anyway, if you lack uber-elite talent at certain spots, maybe the sort of D that Iowa usually runs might be the best way to go against Michigan.  But it seems that Schiano has a more aggressive scheme and it busts a lot without uber-elite guys.  Any D is better with elite guys (duh obvious right?).  But maybe Iowa's scheme works best at a place with pretty good but not elite talent. 

Gotta go in with a well constructed plan to exploit OSU's problems on D! 



November 21st, 2018 at 11:48 AM ^

Brown had the #1 D at freaking Boston College. A solid scheme should work at least fairly well even without elite athletes. If a scheme depends on having better athletes than the other team, well that can work, but only if you always have better athletes (hard to guarantee with injuries and flame-outs) and doesn't exactly require genius.

On the other hand, if your Jimmys and Joes aren't very good, no scheme will work all the time.

Ghost of Fritz…

November 21st, 2018 at 1:58 PM ^

I do not disagree with what you say. 

OTOH it can still be true that certain schemes won't work as well as others with Iowa level talent (good but not elite).  If you have really elite talent then you have more freedom to choose among different schemes, all of which will work (assuming the players are well coached in the chosen scheme, etc).

And of course, whatever the overall talent level, you have to recruit the type of guys that will work in your chosen scheme. 

This may be more visibly obvious on offense (JH scheme works a lot better this year than last with Patterson's ability to extend plays, make accurate throws on the run, etc.).  But it is just as true on D. 


November 21st, 2018 at 10:44 AM ^

Your math is so far off it is ridiculous.

Let's just look at the "with Bosa" red zone number you post - 55.6%.

Do you realize that in EVERY GAME in that period, each opponent did BETTER than that?

Here would be the "real math"

Total red zone opportunities with Bosa = 5 (Oregon St 2 + Rutger 0 + TCU 3)

Total red zone opportunities with Bosa resulting in scores = 4 (Oregon St 2 + Rutger 0 + TCU 2)

Total percentage = 80% (4/5)

This thing is so far off it's crazy.

Unicycle Firefly

November 21st, 2018 at 11:05 AM ^

Yeah, I definitely missed the mark on that one.  Adjusting by taking Rutgers out gives around an 83% conversion rate.  I also re-did the post-Bosa chart since it was wrong also, and got about a 91% conversion rate.  So, not the huge jump I thought at first, but still an increase with him out of the lineup.

The analysis isn't flawless by any means, and I'm certainly not a mathematician or data analyst by trade.


November 21st, 2018 at 10:51 AM ^

Great work. Thank you for taking your time to do it. Another thing to look at would be the frequency of chunk plays. Did it go up or down post-Bosa? Did the plays generate more yards post-Bosa, ie, did 2,3,2 yd plays suddenly become 4,5,6 yd plays? What happened to the 3rd down conversion rate? 

For Red Zone tendencies, remove Rutgers, Tulane and MSU. Then the data shows a scary pattern. Every opponent save Oregon State scored at least 2 TD once they reached Red Zone. And OSU gives up Red Zone TDs at a 67% rate whole year. Their short yardage defense doesn't look good. 


November 21st, 2018 at 11:24 AM ^

this is a nice effort, but you left out one of the fundamental yardsticks of offensive or defensive performance: Yards per Play.  So, I've done it for you and it boils down to this: with Bosa, 5.2 YPP, without Bosa, 6.2 YPP.  That's a meaningful difference, but you also ignore the fact that two of those first three opponents are terrible at football and the third, TCU isn't good at it either.  My reading of it is that Bosa was replaced with someone nearly as good and it's not the difference-maker to OSU's relative collapse in the second half of the season.


November 21st, 2018 at 12:15 PM ^

There is a major confounding factor here: with Bosa, OSU played a terrible Oregon State team (now 2-9), an even worse Rutgers team (1-10), and then he was injured during the TCU game. All the good opposing offenses on their schedule have come after he quit their team.

Their defense isn't good, regardless.  No matter how good Bosa was, it's shocking that a team that reels in top 5 recruiting classes every year looks this bad on that side of the ball.