Thanks to the nflFastR project and NFL NextGen Stats for the timely sources of data. Commentary will be brief but feel free to let me know in the comments that stats aren’t everything. (click charts for larger view)
OK, last one.
His overall efficiency — which is the most important thing — was really good, hitting on key throws that added a lot of value. However, his success rate was poor.
The incomplete on 4th & 4 at the goal line (which analytics said to NOT go for) was his most negative play.
These next charts only hold 17 weeks of data, so week 1 is chopped off and I am far too tired to re-code it.
His 1st down conversion rate and yardage efficiency were above average, but not what I would call good.
The distance on attempts was about league average and distance on completions was longer than average.
The “season” data is weeks 2 – 18.
59% completion rate is about 6 points below expected, same as last week. If 3 of the drops were caught, his completion rate goes to 65% and cpoe = 0.
I changed the chart on the right to show time to throw against not just sack rate, but sack rate + scramble rate. It displays the much stronger correlation between holding the ball and having to abandon attempts.
He was efficient pretty much everywhere. Overall this was a good game for Rivers, just not good enough.
Dropbacks (db): Attempted passes, Sacks or QB scrambles with QB spikes removed.
EPA per Dropback (EPA/db): For any given down, distance and field position, there is an average amount of points the team is expected to generate from that spot (EP). After the play the added EP (EPA) is calculated. EPA/db is the average of EPA for all QB dropbacks.
Passing Success Rate (PSR): This is the % of passes that were successful. Success is determined by dropbacks that have an EPA > 0. This is useful, as it evenly weights all dropbacks, so that extreme EPA events can’t bias the measure.
First Downs per Dropack (1st %): The percent of dropbacks that result in a first down.
Net Yards per Attempt (NY/A): Passing yards plus scramble yards minus sack yards divided by dropbacks.
Air Yards (ayd): The distance a pass travels through the air past the line of scrimmage. Passes behind the line of scrimmage have negative air yards. Batted down passes have 0 air yards.
Average Depth of Target (aDOT): Total air yards divided by attempts. It is a measure of how far, on average, a QB throws. Longer isn’t necessarily better but below a certain threshold and moving the ball is difficult.
Yards Before the Catch (YBC): The air yards on a completed pass.
Completed Air Yards per Attempt: This is average YBC. It’s like aDOT but excludes incompletions.
Yards After the Catch (YAC): The distance gained by a receiver after catching a pass.
Completion Percent Over Expected (cpoe): The percent of passes completed above expectation based on air yards, field placement and other variables. This is a proprietary stat provided by nflFastR.
Time to Throw (TtT): The number of seconds from snap to release on passing attempts.