How Quarterbacks Age

Peyton Manning signed a $90 million contract extension that would hypothetically keep him playing through age 40. Nagging questions about his health will almost certainly plague him for the remaining years of his career. To back up the ailing Manning, the Colts brought in an even older veteran passer, Kerry Collins. In Philadelphia, Michael Vick signed a $100 million contract that will supposedly keep him playing until he's 37. What kind of performance should we expect from older passers?

It's a much more difficult question than it first seems. Averaging the performance of all the recent QBs by age doesn't work. A survivor bias ensures that only the successful QBs stay in the league long enough to have their stats in the sample. Another complication is the the steady inflation of passing stats over the years. In this post, I'll try to tackle those problems to better understand how QB performance is affected by age.

New Game WP Pages

Here's a quick look at a work in progress. It's a redesigned WP Graph page with advanced player stats. It's not done, but it should be ready for the beginning of the season.

Don't Pay CJ!

The word is that Chris Johnson won't be satisfied with being the highest paid RB in the league. He wants to be among the highest paid players at any position. With Larry Fitzgerald's recent 8-year deal guaranteeing nearly $50 million, Johnson must be thinking he's worth something similar. Peyton Manning's recent contract will pay him nearly $20 million per year, and it might make sense to pay one of the greatest QBs of all time 1/6 of your entire payroll. But paying that kind of money to any RB, even the very best, makes no sense.

Adrian Peterson is currently the highest paid RB who is due to make $11 million this season, which is probably two to three times too much. RBs, and the running game in general, do not have the impact on wins and losses the same way the passing game does. But more importantly, the spread between the best and the mediocre RBs is much smaller than the the spread among quarterbacks.

We can't quantify the value of a player the way the MLB analysts can, with Wins Above Replacement and other stats. But we can at least make some back-of-the-envelope, order-of-magnitude estimates.

ESPN's New QB Stat

I, for one, welcome our new statistical overlords.

ESPN has a talented new analytics team, and their first foray into football is their Total QB Rating. It seems the first thing anyone does when they get into advanced football stats is to create their own QB rating system. The QBR is a major improvement over the NFL's traditional passer rating, and there are a lot of things I like about it, but it's not perfect. I'll try to summarize my understanding of the stat, and then I'll list the things I like about it and the things I don't like so much. As we say in the fighter pilot business--the goods and others.

According to ESPN's own explanation, the stat is based on three primary concepts--Expected Points, Win Probability, and division of credit. As I understand it, QBR begins with a QB's Expected Points Added for each play in which he was directly involved, including both pass plays and runs. It modifies each play's EPA value according to a clutch factor, which is based on Win Probability (WP). Here, I use something similar known as Leverage Index (LI). LI is the ratio of the potential swing in WP for a play compared to the average play's potential swing in WP. For example, an LI of 3 means that a play is 3 times more critical to a game's outcome than the typical NFL play. (You can find any play's LI on the interactive WP graphs here by hovering your cursor over the graph. I still consider it a 'beta' stat because I haven't settled on a final, single definition of potential success and failure for every play.)

Top Ten Most Exciting Games of 2010: Cardinals at Rams

Can two of the worst teams in the NFL play a compelling game? Efficiency, after all, though abstract as a concept, is comprised of tangible, felt-in-the-gut events. Inefficient teams suffer missed assignments and general disorganization by their offensive lines. Inefficient teams suffer discordant timing between their quarterback and wide receivers. Inefficient teams suffer poor spacing and reaction time from their defensive backs. The data that inform a 31st ranked passing offense or a 22nd ranked run defense is in fact the distillation of a season’s worth of errant passes, drops, missed blocks, over-pursuit, blown coverages and missed tackles into a number.

So can the worst team in the NFL and the 30th ranked team in the NFL, by efficiency, play an exciting game?

The answer, of course, is yes. And it isn’t “yes” because there are more things in heaven and earth, Brian, than are dreamt of in your statistics. It is “yes” because football is relative, and bad teams tend to burnish each other’s strengths and mask each other’s weaknesses. If only the best of the best talent, playing at the very peak of their ability, in the most expertly crafted and executed system, were able to play a compelling game of football, well then, college football wouldn’t exist.

So surely the Rams and Cardinals could play a compelling game of football in week one of the regular season, but did they? Well, do you enjoy college football? How about a low-scoring slog punctuated by big moments from legitimately great players?

Arizona traveled to St. Louis in week one of the regular season. It was a game filled with portent. It was first overall pick, quarterback Sam Bradford’s first regular season start of his career. Wait, did I write “portent?” I meant to write, it was a game smothered in tacked-on storylines. It was Derek Anderson’s first start as a Cardinal, Arizona’s first chance to defend their illustrious NFC West title, Bradford’s first chance to obscure an expectantly weak rookie campaign with a few sort-of exciting plays, and Larry Fitzgerald’s first chance to sink some poor sap’s fantasy season. It was football and a retrograde strain of it, but it was football and darn it if that isn’t a welcome sight in June.

Unplug

“News is to the mind what sugar is to the body.”—Rolf Dobelli

You may have noticed there has been a labor action here at Advanced NFL Stats. I’m on a work slow-down, taking a vacation from all the lockout noise. Apparently there’s an NFL lockout going on, and there may or may not be full, normal NFL season this fall. That’s all we know, and that’s all we need to know as fans. That’s the signal, and everything else is noise.

Weeks ago I unsubscribed from rumor mills like Pro Football Talk on my RSS reader. I avoid articles in the sports pages about the lockout and change the station when the local sports talk veers into lockout soap opera. Too much of it is gossip, rumor and speculation, and it’s a giant waste of time.

What Happened to the First Round RB?

In the five-year period between 1970 through 1974, running backs made up 20% of all first round NFL draft picks. That's one out of every five. As recently as the 1985-1989 period, RBs made up 19% of first rounders. But by the most recent decade, from 2000 through 2010, RB selection was cut in half--down to about 10%. Last night, only 1 of the 32 players chosen (about 3%) was a RB, and he was chosen 28th, near the bottom of the round.

The graph below illustrates the trends in how teams favor each position over the past 41 years. Most positions are fairly stable. Click to expand.

Draft Needs According to 2010 EPA - Defense

Measuring defensive players is trickier than offensive players for a couple reasons. Most notably, +EPA (Positive Expected Points Added) captures half the story at best. But the idea is that the part of the story we see will correlate well with the part we don't see. In other words, "playmaking" defenders, in most cases at least, are often making unseen impacts as often as they make prominently visible plays.

The table below lists the 2010 regular season +EPA totals for each team by position. Although it doesn't consider free agent losses or injuries, this might be considered a good starting point for determining defensive draft needs.

Unfortunately, defensive positions are not so cut-and-dry. Depending on the base scheme, there are varying numbers of DEs, DTs, and LBs. (The 49ers don't even have a DE position.) Plus, players can sometimes be designated different positions from week to week. Advanced NFL Stats ultimately classifies players according to their most frequent designation in each game's official playbook.