Christian McCaffrey in 2018 Le'Veon Bell 2019.
...
CMAC was amazing,
~440 FFPts.
Top 2 back [with Saquon].
...
Last year Bell was a massive disappointment.
276 FFPts.
RB16.
...
I think the 2 seasons were way more similar than most people think.

Here's carries and rushes for the 2 players.
CMac had 50 more targets.
Bell had more carries.
In the end CMac had 326 touches.
Bell had 311

Rushes/targets by down.
Pretty similar eh?
Certainly no major proportional difference

Here's the data by down in a different way.
More CMac on first down was the main difference.

So it adds up like this.
2018 CMac had the extra targets - mainly on early downs.
Bell had more rushing on 2nd/3rd downs

Targets/rushes by yards to go.
No huge differences here really

Yards to go split another way.
Super similar.
Neither of them was some sort of short-yardage back or anything.

Comparing usage by week.
Really similar, steady volume.

Looking at rushing attempts by gap
CMac rushed more in the A gaps.
Bell more off to the right.

But here's the real big difference...
2018 CMac had the big plays.
2019 Bell did not.

And shown as a proportion.
This is such a huge difference

And the same data just on count of plays by yardage bucket.
2018 CMac had those 16 big plays.
2019 Bell managed just 2.

The point is - volume and usage are really similar. They were used about the same amount, in a similar way [with some differences obviously].
But one player had the big plays and one did not.

Big plays come to better RBs more often - but it's not a major rate.
The predictive power of volume is WAAAY better than 'talent' or 'skill'.
And some of what makes us think a player is amazing in the first place is how lucky he got with his big plays

Alvin kamara in his forst 2 years.
Saquon as a rookie.
They had loads of big plays and we thought they were spectacular.
They both had a down 2019 and we asked "what happened to him?"

That's the wrong way round.
We should assume average big play rate - and then be pleasantly surprised when players overproduce.

But because often it's young RBs who have the big plays we love to think that each of those particular players is special and just naturally will do it because of his talent.

Volume is king.
But when we get outliers we like to convince ourselves that they prove a narrative.
Reality is so much less about ability - and more about volume and luck.