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)
This chart disagrees with itself. Philip Rivers EPA efficiency was pretty good but his success rate was poor. Basically, he had more bad plays then good (more red plays than green) but the value of the good plays was higher than the value lost on the bad plays (green area > red area).
This means that he didn’t play well overall, but he made some key plays.
The biggest takeaway here isn’t depth of target, which was good, but incompletions which were numerous and happened primarily on short passes.
Rivers’ avg depth of passes and air yards on completions is growing which is a good thing.
His completed air yards per attempt puts him right about the middle of the pack, but it is yards per attempt (the total bar height) that truly matters.
With 25% of the season gone, Rivers has yet to hit the end zone from anything other than short distances.
Passing value is being derived from RBs and TEs. Until the WRs can add value, the passing game won’t be a threat.
The critical passing stat from this week is the drop in accuracy.
Quick release and minimal sacks is the preferred combination.
Ironically, Rivers was better the deeper he threw.
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.