There was a thread here about the conflicting offensive line rankings of different analytics. I thought this would be a good chance to discuss what analytics is for (and what it's not).
Analytics is just information. All it's doing is providing different information with better context.
For example, using yards (or even points) to judge an offense or defense is too simplistic to be useful. If a offense has 3 drives start in the opponents end because of TOs, they're going to score more than an offense that started every drive on their own 25. Context.
At the same time, while we can use "rankings" and "grades" as short-hand for performance, ideally they need to be understood for what they are measuring. PFF, FootbalLOutsiders's adjusted sack rate, and ESPN's Pass Block Win Rate are all measuring slightly different things about an offensive line. That they might give us different information isn't a bug, but a feature.
For example, FootbalLOutsiders itself will use both it's Adjusted Sack Rate and ESPN's PBWR when discussing and evaluating offensive lines.
One of the challenges of evaluating offensive line is that the scheme and QB have a huge impact in run and pass blocking. The broad consensus in analytics seems to be that sacks are primarily a QB, not offensive line, stat. Because the QB has the ability to get rid of the ball almost every time before taking a sack, he has a lot of control over taking a sack (in over 2.5 seconds). This is also a big reason why Brees' OL is always so good - Brees gets the ball out insanely fast.
Arians scheme is also very unfair to OL. Arians has never had a "good" OL and its no accident that Arians' QBs take a lot of hits.
----------------------------
Looking at the analytics:
PFF has the Bucs offensive line as ranked 7th in 2019. That's impressive.
Yet FO has the Bucs as 23rd in adjusted sack rate and 22nd in line yards (rushing).
ESPN's Pass Block Win Rate has the Bucs at 17th.
----------------------------
PFF: What PFF is telling us is that based on their (subjective) grading system, the Bucs players individually graded out as the 7th best starters in 2019.
This includes pass and run blocking. The Bucs OL definitely graded out higher in pass blocking over run blocking.
It's worth pointing out that every grading system is subjective, and the PFF system has a few advantages. (1) They watch every team (2) they're not biased and (3) we can compare it across multiple years.
The disadvantage is that, because it's broad, it's not factoring in the specific requirements of scheme. What Bruce Arians and Sean Payton demand of their OL is different. As well, it's not telling us how they performed as a unit. And of course, we don't know the exact reasons why Marpet or Jensen or Dotson were graded why they were.
FootbalLOutsiders: First, FO's "Adjusted Sack Rate" (ASR) is "sacks (plus intentional grounding penalties) per pass attempt adjusted for down, distance, and opponent."
I'm less of a fan of this because sacks are highly variable. For example, Shaq and Za'darius Smith both had 37 QB hits but Shaq had 19.5 sacks and Smith 13.5.
The Bucs were 22nd in sacks AND 22nd in ASR. So, the sack total is reflective of where the Bucs pass blocking performed. It's important to note, this does not separate out the QB (or even the RBs). This is important because Winston had the 7th longest time-to-throw at 2.77 seconds. On top of which, per PFF Barber and RoJo had very bad pass blocking grades.
So, we have a bad pass blocking unit per FO. Based on context (D&D, attempts, etc) the pass blocking wasn't great. But how much was the OL? How much the QB? The scheme? The RBs? By bringing in other analytics like PFF, we can see the story is more complicated and the OL's "stats" were hurt by both the QB/scheme and the RBs.
A quick note on FO's run blocking stats. Here, the offense itself was 27th in run blocking, the Bucs best back ranked 23rd, and the OL ranks poorly in their stats.
The cool thing about FO's run blocking stats is how they're broken down: by OL, RB, power runs, stuffs, 2nd level, open field. But it also means you have to do some digging to understand what is happening (no easy ranking). Without going into detail, FO's stats suggest the Bucs OL was below average (not terrible) in run blocking and the backs stunk. A counter-stat is the Bucs OL was 30th in stuffed runs, which is terrible.
ESPN PBWR: I really like Pass Block Win Rate and think it's a huge addition to evaluating offenisve line.
The argument is simple: Using NextGen stats data, how often is the offensive line holding their blocks for 2.5 + seconds? That is the rought measure of how long an offensive line should be sustaining. Beyond that, you're asking a lot of OL.
The Bucs ranked 17th. This came down from earlier in the season when the Bucs were top 10 for a while.
So the Bucs are right around average in terms of sustaining their blocks. This suggests that the Bucs scheme and/or QB is asking more of the OL and increasing the sack totals. That being said, the Bucs OL isn't great. Not bad, not great.
----------------------------
CONCLUSION
I think the Saints provide a useful example of what we're talking about: the Saints with their vaunted line are 25th in ESPN's PBWR. Which again, if we take this data seriously shows the impact the QB has on OL sacks - the Saints are 3rd in FO's adjusted sack rate!
Yet, PFF grades have the Saints OL 3rd and say that the OL was great in under 2.5 seconds.
This is why no analytics person thinks you can just look at "stats" (especially a single stat). You have to use your football knowledge to tease apart this information. To me, it seems the PFF OL data really factors in Brees quick release (which ESPN does not via their use of NextGen data). The Saints have a good pass blocking OL that is really, really helped by QB/scheme.
Conversely, the Bucs have an average pass-blocking OL that is hurt by QB/scheme as well as bad pass-blocking RBs. Further, the unit is bad at run-blocking and made worse by bad RBs.
Ultimately, it's really really hard to separate out scheme vs. QB. We know that Arians schemes have always asked the OL to sustain blocks a very long time (long enough to pile up sacks). But Winston also has a long habit of holding onto the ball and has had a long "time to throw" every year.
We arrive back at a place I think we agree in terms of common sense. The Bucs OL needs a talent infusion at the tackle spots (PFF), it struggles in the run (FO), and is made worse by scheme/QB (ESPN).
