Thread by @TomKislingbury

I did a thing.
I wanted to look at how much injured QBs affected coaches and teams. So I did some fiddling with data from the past few years.
Here we go
#Thread

My method was fairly simple.
I went back through the past 4 years [I had the data handy] and looked at how often starting QBs missed games through injury.
I looked at the PFF grade for the starter and the replacement.

I restricted this to QBs who were hurt rather than dropped.
Obviously there's some grey area there.
Remember when the Bears dropped Trubisky and said he was hurt?
There's an element of interpretation here.
It's not 0% subjective.
But I tried to be as clear as possible

I counted games where either QB [the starter or the replacement] played at least 10 snaps.
You get into the territory of deciding which games count and which ones don't. Starts. Vs games played in, vs majority. Etc

I ignored games where the backup was brought in for replacement snaps for strategic reasons. For example when the Ravens gave Lamar Jackson playing time before he was the starter.

In instances where a QB missed the whole season [Ryan Tannehill in 2017] I used the PFF grade from the season before.

In the last 4 years I counted 200 instances of injury replacement QBs.
50 games per season.
That isn't huge and sample size is an issue but it's not the worst. 200 is a big number here

For those 200 games there were 53 different replacement QBs.
So on average they played slightly under 4 games per starter injury.
Obviously some fewer and some more

Of those 53 replacement instances the average dropoff was 18%.
The replacement was 18% worse than the starter.
But actually in 8 of the 53 cases the replacement was BETTER than the starter

Those included:
CHI 2016 - Brian Hoyer for Jay Cutler
2018 MIA - Brock Osweiler for Ryan Tannehill

Anyway - on average we can expect the replacement QB to be about 20% worse than the starter in PFF grade terms.
Seems reasonable to me

The next step was to look at which coaches had it worst.
It makes sense to me that some coaches can cover QB injury better.
If they're a better coach they can probably get the replacement looking not so bad.
This is literally coaching in my book.

This is average dropoff by HC.
Note I restricted this to HC.
Ascertaining whether the OC or QB coach or HC owns the blame or credit is subjective.
The HC is ultimately responsible for coaching the players.

This lacks context though - because some of those replacements were for more or fewer games.
So this version shows both:

And sorted by replacement QB games.

By this you can see that Adam Gase has indeed had the most replacement QB games over the past 4 years [although 16 of the 28 were Tannehill missing 2017.

Unfortunately for Mr Gase he has been middling for replacement quality.
Osweiler in 2018 was better than Tannehill.
Luke Falk in 2019 was even worse than Sam Darnold [who was already horrible].

So on average his replacement QB was 15% worse than the starter.
That's actually slightly better than you'd expect.
So good job!
Although the fact that his starting QBs were so bad in the first place means it's easier to not drop off much.

But away from coach Gase it sort of makes sense.
Near the top end we see Kyle Shanahan and Frank Reich.
Near the bottom we see Matt Patricia, Mike Mularkey, Marv Lewis, Rex Ryan, Jack Del Rio.
There are other exceptions and I'm cherrypicking here but it fits what I expected

Some of the exceptions:
John Fox at the top.
When Jay Cutler missed two thirds of 2016 Brian Hoyer and Matt Barkley outshone him.
Belichick at the bottom.
This is unfair though.
Jimmy G and Jacoby Brissett were not as good in 2017 as vintage Tom Brady. Well duh.

Some of this can be explained by just looking how good the starter was.
For the elite QBs the dropoff was bigger. [Brissett was nowhere near as good as Brady, Teddy B not as good as Drew Brees in 2019].
For bad QBs it was much flatter [2019 Cam Newton was pretty easy to replace]

Anyway.
The whole "Adam Gase is a good coach but was hamstring by QB injury" seems suspect to me.
2017 was bad.
Fair enough.
But actually Darnold only missed 2.5 games last year.
Tannehill 5.5 in 2018 [and his replacement was better than him] and 2.5 in 2016.