OZ CHAOS LEADS TO MORE GOALS
(Oct 2017)
This can be attributed to net accessibility caused by unscripted offensive-zone play, which in many ways is becoming the new script in the NHL.
We see defensemen doing that a lot now, abandoning the blue line to go lower in the zone. These players, the defensemen especially, are thinking that they don’t have to be the high guy, the safety valve.
They’re taking a risk to help their team get a better chance to own the net-front area and create chaos for the team defending, especially since the fourth man in the rush is staying in the play.
It used to be about crashing the net, but now it’s about throwing the puck at the net and hunting the puck down for rebounds. Then, like on a power play, regaining control of the puck as quickly as possible to regroup and doing it again if it didn’t work the first time.
All teams are trying to access the net through unscripted play in the offensive zone. Goals are up as a result.
USING DATA TO INFORM OZ DECISIONS
The decision on how to set up and attack in the offensive zone is largely determined by the coach. They will establish a structure within which their players have some latitude to create offense.
Two types of common attacks: Behind the Net strategy, which you’ll see the San Jose Sharks using, and the Low-to-High to Net strategy,
Low-To-High Plays In OZ
when faced with a team that brings all five players below the tops of the faceoff circles, passing the puck back to the point will force one or two forwards to come out and press the points, thereby creating space behind them for passing lanes to open up.
This is a strategy used to draw the defense out from their collapsed box and reassess options.
Behind-The-Net Attack
An aggressive 2-1-2 forecheck, gaining possession of the puck, followed by a strong cycle game.
The key tactical advantage in playing behind the net: Come from the weak side and circle behind the net, receiving the puck below the end line.
Move behind the net to receive the puck. Most teams won’t send someone back there to check the opponent as it leaves the front of the net unprotected. It forces the defenseman to make a tactical decision of “Remain or Leave?”
Behind Net vs Point Shots
from behind the net, they are converted 12.8% of the time compared to shots on target from the point that are converted at a much lower rate of 4.1%.
To quickly recap: you are more likely to score and generate rebounds by playing behind the net rather than going through the point for offense.
how teams pass the puck to generate offense is repeatable, which makes sense given that play in the offensive zone is largely dictated by the coaching staff beforehand.
If your plan is to score goals and create rebounds, play behind the net.
SEQUENCES AND THE HOCKEY DECISION TREE
Roughly, every time the puck changes possession between teams, a new Sequence” begins. That’s about 250 Sequences per game.
A sequence includes: a zone exit, a zone entry, a high danger pass, a shot assist, a shot.
· Successful carry exit: 0.064 Expected Goals happen in average
· Failed dump out: 0.076
· Successful zone entry in control: 0.067
· Successful high-danger pass: 0.129
So After defining the average Sequence’s Expected Goals value, the second part of the equation is to look at how often each event leads to a shot attempt, and there we can see logical differences:
· A successful carry exit leads to a shot attempt 37% of the time
· A failed dump out: 4%…
· A successful zone entry in control: 60%
· A high-danger pass: 87%
In the end, the successful carry exit is worth 8 times more than a failed dump out, and a dangerous pass is worth over 4 times more than a successful carry exit.
Here are the point values in Expected Goals for all events included in a sequence:
High Danger Pass = 0.133
Controlled Entry = 0.04
Pass Exit = 0.026
Carry Exit = 0.024
Dump Entry = 0.022
Failed Pass Exit = 0.007
Failed Dump Entry = 0.006
Failed Controlled Entry = 0.005
Failed Carry Exit = 0.003
Failed Dump Exit = 0.003
BAYESIAN MODELS FOR EXPECTED POSSESSION ADDED VALUE
1. How do offensive sequences develop? (Markov decision process)
2. How do we determine which event will occur next in a sequence? (transition probabilities & INLA)
3. How does the spatial, time, and contextual information develop? (space/time/context models)
4.What is the value of a sequence at a particular moment? (xG models, xPV, and simulations)
5. How much value does an event contribute to the offensive potential of a sequence
Rush vs OZ Play
The first few seconds following a zone entry are the most dangerous: during this time period, the slot area is expected to be very valuable.
If a team manages to access this area of the ice on the rush, they should expect to be able to create a very dangerous offensive sequence.
Passing Plays:
As a result, we can see on the figure above that the vast majority of passes in the OZ happen along the boards, through low to high or high to low plays,
To put it simply, passing from high-value areas to low-value is easy; passing from low-value areas to high-value areas is difficult and does not successfully occur often.
Perimeter passes, which make up the bulk of all passes, neither increase or decrease the value of a possession significantly since they do not infiltrate the high value regions
That said, passes which greatly improve the condition of the puck are some of the highest value plays possible and players consistently able to do so can have large PAV passing values
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