Just How Valuable Are Centers In Football?
So if you all don’t know by now I’m a Giants fan. The way they’ve been playing has been uninspiring at best, leading to a lot of early draft talk for us. One name that’s been brought up a lot is Tyler Linderbaum. The center from Iowa has been downright amazing and has been an outlier in terms of PFF’s Wins Above Average metric. His 95.3 PFF grade this year is the highest from any center in PFF’s eight years grading college players. Ironically enough, he was recruited to play interior defensive line, but moved to center in 2019. Many Giants fans want to take him with one of our first-round picks, but center typically isn’t a position drafted that high due to positional value.
PFF’s WAR (Wins Above Replacement) metric is also low on centers in terms of positional value. In fact, in 2020, centers added the least wins, seen below:
This feels wrong though. Certainly, centers are more important than running backs, the position analytics twitter has deemed of no importance. If you ask most football players, especially quarterbacks, they would tell you that centers are vitally important to their team. Mike Sando, a reporter for The Athletic, stated that most NFL teams think centers are the 2nd or 3rd most valuable position on a team. Just recently, I conducted this Twitter poll to see what my followers thought:
About 14% voted for very valuable, 70% for the middle of the pack, and 16% for not that valuable. It makes sense, I would have voted for the middle of the pack as well. Yet, the disconnect between how some people, including PFF’s metric, versus football players and coaches, view the center position is real. I think there’s a lot more to it, so I’m going to try to break it down a bit more. Here goes.
What’s the Center’s Role?
This section is fairly simple, let’s define what a center’s role is in football. There are four main things in my opinion that they are responsible for. It’s best to think of centers as the captain or leader of the offensive line. They are the ones scouting out the defensive line, communicating any necessary protection shifts, and blocking adjustments to the rest of the line, which is the first thing and the most important. Without the center’s guidance, the other members of the offensive line would be left scrambling trying to figure out how to adjust protection and counter the defensive front. This stuff doesn’t show up in PFF’s evaluation of centers, likely contributing to the aforementioned disconnect.
Next, they are also obviously responsible for pass blocking and run blocking just like every other lineman, which falls in at two and three. Additionally to this point, centers are also facing up the largest men on the football field, whether it be defensive or nose tackles.
Coming in at four, centers have to have a great relationship with their quarterback. This seems crucially important regarding the timing of a play and the process of getting the ball snapped. Time after time, we’ve seen how mis-snaps can not only stall a play but the whole drive. The following is a great example:
Miscommunication between the center and quarterback not only leads to a loss of yards, but a safety, an awful swing for the Cardinals. Again, not necessarily something that goes into PFF’s grades to my knowledge, but it definitely does matter.
A lot of the center’s role is just football intangibles. Stuff like shifting your front or pointing out a blitz won’t show up in a box score or PFF grades. I don’t even think it’s a thing that film can tell us a lot more about, we can’t analyze in real-time what’s going through a center’s head. But, we can accept that there are some things we can’t measure. In addition to the point above, we also struggle to analyze the connection formed with their quarterbacks and how that might impact play. It’s not bold to suggest that quarterbacks and centers that have been playing together for a long time are more likely to be on the same page and have great timing with each other. Yet, we still can’t fully capture this in a stat like pass blocking and run blocking grades or ESPN win rates, and that’s okay. We just need to keep this context in the back of our heads.
Well, What About The Stuff We Can Measure?
Now that we’ve covered a lot of the traits we can’t measure about centers, let’s hone in on the stuff we can measure. I’m going to lean back into PFF’s pass blocking and run blocking grades as the stats I use. This is one of the best resources to measure OL play in my belief mainly because not everyone can watch every single game, there aren’t many great public OL stats, and NFL teams do use PFF’s metrics. At the same time, it has flaws as OL expert @GabLikesFball pointed out to me. These include but aren’t limited to: not accounting for the quarterback’s effect on the line and. misgraded plays skewing an already small sample. It’s not perfect, but it’s the best I got.
Anyways, what I did is fairly simple. I organized a large data set, consisting of the years 2019–2021 (the present). This data set possesses each team’s pass blocking and run blocking grades each year, and the corresponding center’s pass-blocking grade and run-blocking grade. I then graphed the center’s skill against that of the whole team, mainly the offensive line, to see how much the center’s ability mattered. You can see this below with the first year, 2019:
On the left is run-blocking, and pass-blocking is on the right. Weirdly enough, the pass-blocking correlation of 0.3 was an outlier compared to every other comparison. Even so, it’s clear the center’s play correlated strongly with the team’s play. Let’s do it again with 2020, and 2021 right after.
I’ll list out the correlation values here as they’re likely blurry. In 2019: run blocking = 0.68 and pass blocking = 0.3. In 2020: run blocking = 0.6 and pass blocking = 0.61. In 2021, run blocking = 0.56 and pass blocking = 0.56 as well.
Regarding correlation values, typically anything over 0.5 is good, but ideally, you get values over 0.8 for a really strong correlation. However, football isn’t a very stable game. There’s a lot of moving pieces and variability. That’s why most football analysts are quite satisfied with correlation values between 0.4 and 0.6. Let’s simplify those correlation values even further into averages, with run blocking coming in at 0.61 and pass blocking coming in at 0.49. I’m really encouraged by both of these values.
The disparity between run blocking and pass blocking that we can see is one that is definitely worthy of consideration. My educated guess is that it’s due to the effect of the quarterback on his offensive line when passing. Most know that sacks are a measure of the quarterback, not the line. The quarterback is the one holding onto the ball, maneuvering in the pocket, and evading (or not) pressure. I think that’s why we see that the center’s play is less correlated to his whole line’s play in passing scenarios: because the quarterback matters a great load in those situations as well.
And now, for what’s it worth, I applied this same method to tackles and guards as well, weighting the average by snaps played for each tackle:
Honestly, my initial reaction to this was “huh?”. Not in any scenario did I envision guards to do that well and tackles to be that low. I have a couple plausible explanations in mind, such as scarcity at the guard position, the effect great offensive line coaches can have, and again, the effect of the quarterback on the line. One that’s a solid, and likely the best, explanation, courtesy of @Martentoellner on Twitter, is that guards are most dependent on the run blocking and pass blocking around them, then centers, and then tackles. This would mean that tackle play is the most independent, seen in the lower correlation. Very possible!
I can’t stress this enough though. This doesn’t mean guards are more important or valuable than centers and tackles. All this is is a correlation test, a descriptive value. So yes, guards correlated better over the last three years. However, this is in no way a predictor or anything of the sorts. It’s just what happened. It could easily come out different if I analyzed a different three years.
One thing I do want to note though is that you have only one center playing at a time versus two guards and two tackles. And the importance of elite center can’t be understated in any way. For example, the Chiefs hit a home run when drafting Creed Humphrey in last year’s draft. He has a 91.6 PFF grade already, and coincidentally, the Chiefs’ OL has completely turned around from the mess it was last year. Not all credit should go to only Humphrey, but he certainly deserves a large part of it. (This is why I’d be content, perhaps satisfied, if the Giants took Linderbaum, to answer that question.)
Furthermore, center looks to be a tough position to play really well. Really quick way to look at this is the average number of players at each respective position that have graded above 80 since 2019. Center clocks in at roughly 3 players, guards at 6, and tackles 15. Essentially, we’re seeing a lot more solid tackle play than we are guards and centers by PFF’s standards. It’s worth keeping in mind. It’s not to say that tackle play becomes “replaceable”, which it certainly doesn’t, but due to the scantiness of elite play at center and guard, finding an elite player at those spots would be a great advantage. If I had the means, I’d definitely want to dive into if interior OL is more valuable than we’ve thought, given the proven scarcity at IOL and the intangibles of the center position. Someone smarter than me should pick that up.
Anyways, what can we take away from this? Well, for now, it’s fair to say that a center’s play matters very much. We found a solid correlation, not causation, in the past three years between a center’s success and the rest of the line. Theory wise, it isn’t hard to believe that having a great center bodes well for the rest of the team, especially considering the platitude of pre-snap adjustments that they’re solely responsible for.
How much does it exactly matter? Not sure. I don’t have the data, skills, or time to answer that question. Certainly more than I’ve thought though. In the twitter poll way above, I mentioned 12 position groups. The only ones I’d have definitely above centers are quarterbacks, wide receivers, cornerbacks. Then, I’d be pretty torn with the edge rushers, tackles, and guards (could be convinced, though). Definitely in the upper half of position groups’ importance.
I’d bet most people at PFF disagree with their WAR metric’s evaluation of centers, and I’d like to see how that evolves over time. Maybe that turns into a more reliable, public way to measure play. Centers affect not only themselves and their quarterback but the whole offensive line too. They are responsible for so much that we can’t measure at this time. This is largely why Tyler Linderbaum wouldn’t be the worst pick, he’d provide stability to a team that needs it. Not my first choice, but not by any means a bad selection if it’s not too early in the 1st.
And honestly, as lame as it might be, I think that’s my main takeaway from writing this piece. There is so, so much about OL play that we can’t measure through stats. Pressure rate, PFF grades, and win rates are all great stats! Yet they still fail to tell so much of the story. As my conversation with @LuckyProphet5 on Twitter unfolded, we both agreed on the fact that trying to quantify players within a unit is quite hard given the confounding factorsthat exist in football. Basically, it would make more sense to just evaluate the offensive line as a whole for now as opposed to centers vs guards vs tackles until we come up with better metrics and quantifying methods.
But to leave you all with something definitive, I’ll say this. Centers are more important than I thought before writing this piece. Nonetheless, there are still many steps to cover before we can concretely evaluate offensive line play through statistics, and I look forward to when that day comes.