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The
Statistics of Dumping
by Jim Parinella
I estimated throwing percentages (with a high stall count) for three categories
of thrower (great, average, and poor) for four different length passes (40,20,10,
and -5, with four different rates for the dump), then estimated scoring rates
for three types of teams (great, average, and poor) from 5 different spots
on the field (10,20,40,60, and 70 yards away from scoring). I thus estimated
the team's chances of scoring for each choice of throw. I included a penalty
for short turnovers to reflect the fact that the other team will have less
ground to cover to score.
Chance
of scoring from the x yard line
|
Yard
Line
|
70
|
60
|
40
|
20
|
10
|
|
Great
|
0.5
|
0.57
|
0.71
|
0.86
|
0.93
|
|
Average
|
0.3
|
0.4
|
0.6
|
0.8
|
0.9
|
|
Poor
|
0.07
|
0.2
|
0.47
|
0.73
|
0.87
|
Chance
of a player completing a y yard pass
|
Yards
|
40
|
20
|
10
|
-5
(4 different ones)
|
|
Great
|
0.4
|
0.75
|
0.85
|
0.98,0.95,0.9,0.8
|
|
Average
|
0.3
|
0.6
|
0.75
|
0.98,0.95,0.9,0.8
|
|
Poor
|
0.2
|
0.45
|
0.6
|
0.98,0.95,0.9,0.8
|
At
first glance, these completion rates may appear low. However, they were chosen
to reflect the difficulty of completing a pass at a high stall count, which
is when the dump should be used.
Scoring rate is 100% at epsilon yards away from the goal line, and decreases
linearly with every yard further away.
Completion rate for a particular throw is independent of location on the field.
Everything is linear.
At Nationals one year, the Open division had a completion rate of 88%, and
the Women completed 82.5%. Goal scoring rate was about 90% once a team crossed
the 10, about 35% from their own goal line.
In almost all situations, when the dump completion rate was at least 90%,
the better team strategy was to dump. The primary exception was when the thrower
was in a class higher than the team (great thrower on average team, for example).
A great thrower on a poor team will help the team more by throwing it downfield
at 75% or 85% than by taking a 100% dump.
On a great offensive team, even a great thrower will help the team by dumping
it. Even if he can complete 85% of his 10 yard stall 8 throws, which is extremely
unlikely, he would only need to complete 95% of his dumps to come out ahead.
If he is deciding between a 75% 20 yarder and a dump, the break even point
is between 91 and 93%.
Poor teams tended to benefit more by dumping near the goal line, and taking
the riskier throws away from the goal line.
Being able to dump will increase a player's value to almost every team. A
high percentage dump pass, even though the team is further away from scoring
than before and thus will have a lower likelihood of scoring, is often the
best option available.
In general, if a team is likely to score, a conservative option should be
chosen. If a team is unlikely to score, the higher risk, higher gain pass
should be taken.
If you reran the numbers using completion rates at all stall counts, the dump
would probably be advantageous only for poor players on good teams. But this
article is looking at the use of the dump as a high stall count option.
References
Jim Parinella
http://www.upa.org/upa/totw/tip8.html
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