Help Us Play Better Defense!
Should you move to shooters, or hold blocks? Different coaches have different philosophies, and coaches’ philosophies are often affected by game scenarios. Generally, moving to perimeter players extends the defense, which in turn frees up post players in power plays and puts centers in positions from which they can more easily receive entry passes. On the other hand, holding blocks allows perimeter players to get closer to the cage and move the ball more freely without pressure. So, which philosophy should you adopt?
This post discusses how defensive players’ positions affect shooters’ scoring odds.
What is defense?
There are 5 different defensive scenarios that affect shooters’ scoring odds:
Field Blocker: A blocker directly in front of the shooter (e.g., direct shot or shooting in a zone);
Blocker at Distance: A blocker more than 3 meters away from the shooter attempting to block the shot (e.g., center defender helping block a shot from the perimeter);
Contested: An offensive player getting hit while shooting;
Pressured: A defensive player attacking the shooter from the side or behind (e.g., split or chasing a transition); and
Uncontested: A shot taken, and no defensive players affecting the shot (e.g., 1-0).
Often there are multiple defensive scenarios affecting one shot. For example, when a direct shot is taken, there is usually a Field Blocker (defensive scenario no. 1) and a Blocker at Distance (defensive scenario no. 2).
Defensive Scenario Study
A recent study by Joey Gullikson, evaluated the effects of the five defensive scenarios discussed above on players’ shooting percentages. For each shot, the study tracked and evaluated the defensive scenario that most impacted the shot. The study found that there’s no difference between Field Blocker (defensive scenario no. 1) and Blocker at Distance (defensive scenario no. 2), so for the remainder of this post, the Field Blocker defensive scenario will encompass both the Field Blocker and Blocker at Distance defensive scenarios. Now, what does this mean for shooters?
Unsurprisingly, the study revealed that Uncontested (defensive scenario no. 5) shots had the highest scoring odds of any defensive scenario (about 70%), followed by Pressured (defensive scenario no. 4), Field Blocker, and Contested (defensive scenario no. 3), in that order. Pressured shots had a predicted 59% decrease in scoring odds from Uncontested shots. Field Blocker and Contested scenarios led to additional decrease in scoring odds of about 5% and 10%, respectively. For example, if a player took 100 uncontested shots and 100 pressured shots, the player would score about 70 Uncontested shots and 43 Pressured shots. You can see—defensive players’ positions have a tremendous impact on shooters’ ability to score.
Good vs. Bad Shots
We have all seen a player (or—cough, cough—been the player) that catches the ball, attempts to shoot, and gets hit by a defensive player mid-shot...The end result is the ball landing directly behind the defensive player, and never even reaching the goalie. This is a bad shot. How do you avoid this?
You need to think about three main factors that affect a player’s ability to score: (1) the assister (lock the goalie, correct timing, and good pass); (2) the shooter (position in the pool, skill level, situation, and type of shot); and (3) defensive scenarios (Contested, Pressured, Field Blocker, and Uncontested). In practice, this means some situations that have high scoring odds may get passed up (because of the assister, shooter, or the defensive scenario) for situations that have lower scoring odds, in hopes of ultimately setting up a situation with even higher scoring odds than the initial high scoring odds option. For example, a player may pass up a counter attack opportunity to pursue an even scenario, in hope of ultimately setting up a power play, penalty, or the like.
Figure 1. Heat maps of predicted probabilities for normal, right-handed shots against different offensive/defensive scenarios.
Figure 1 compares the predicted shot probabilities for right-handed normal shots (i.e., shots thrown at full power that did not hit the water before reaching the goal or goalie) taken against different defensive and offensive scenarios (separate post on offensive scenarios forthcoming). For example, as shown in Figure 1, the average goal-scoring probability for all shots in the study was about 33%. See the light blue regions in the heat maps, which serve as a cut-off for distinguishing between “good” and “bad” shots. As you can see, a Contested shot under an even scenario is only a “good” shot if taken within the goal posts and inside the five-meter line; and an Uncontested shot in a power play scenario is usually a “good” shot.
What if a player is left-handed?
Then the player will undoubtedly be a First Team All-American, have 4 National Championship rings, make the National Team, and go on to win an Olympic gold medal. Everyone knows that lefties are better...The study evaluated right-handed vs. left-handed scoring rates, and actually disproved this myth.
It found that the discrepancy between the two likely has more to do with defensive scenarios than with any inherent benefit to left-handed shots. Since right-handed shooters greatly outnumber left-handed shooters, goalies and field blockers get more practice defending against right-handed shots. To test this hypothesis, the study reclassified all missed shots in the database according to whether they missed because of a field block, a goalie save, or an off-target shot. Doing so revealed that left-handers shot off-target at roughly the same rate as right-handers (24% vs. 25%), but their shots were saved at a slightly lower rate (24.5% vs. 28%, p-value of 0.023). Field block rates were also lower for left-handed shots, although the difference was only moderately significant (6% vs. 8%; p-value of 0.094).
The study also evaluated right-handed vs. left-handed scoring percentages during power play situations and defensive scenarios. Under Uncontested and Contested power play situations, right-handers scored about 68% and 38% of the time, respectively; and left-handers scored about 80% and 47% of the time, respectively.
Based on this study, it seems that one simple method of increasing a team’s defensive ability is to dedicate time to field blocking left-handed shooters. Since most athletes are instructed to “mirror” the shooter (shooter is right handed, so blocker blocks with left arm—or visa versa), then it is advisable for a team with no left-handed shooters to design field blocking drills that force athletes to block with both their right and left arms. Field blocking is a skill much like shooting, so working on reaction time and fast twitch muscles in both arms is important for athletes’ development.
How should a player defend shots?
As discussed earlier in this post, Contested is the defensive scenario that has the greatest impact on offense, then Field Blocker, Pressured, and Uncontested, in that order. So, one adjustment a team can make that can help lower the scoring percentage of their opponent is to storm on 6 on 5 instead of holding a blocking scheme. By storming, a team (a) puts itself in position to Contest perimeter shots and (b) distresses an assister, thereby utilizing all three factors that affect scoring percentage (i.e., assister, shooter, and defense). In order to do this successfully, defensive players need to (1) anticipate passes, (2) communicate with their teammates, and (3) have proficient technical mobility skills (i.e., ability to move to a shooter and recover when the perimeter player does not have the ball).
Teams should attempt to Contest as many shots as possible. Contesting shots (1) decreases an opponent’s odds of scoring, and (2) puts defensive players in position to create counter attack opportunities (e.g., gross and go). By developing players’ mobility, teams can disrupt more offensive opportunities and create offensive advantages.
Winning!
A typical men’s collegiate water polo game contains around 30 shots per team, with about 14 coming from Field Blocker opportunities, 8 from Contested shots, 5 from Pressured shots, and 3 from Uncontested shots. By passing up 2 Field Block shots and 2 Contested shots per game and, instead, working for 2 additional Uncontested shots and 2 additional pressured shots, a team can increase their average goals per game by more than 1 goal. Championship games are often won and lost by 1 goal. So, detailed shot data can help teams make more informed decisions about which shots are worth taking, and ensure teams do not “throw away their shot” at victory.
Reference:
Joey Gullikson, John. K. Mayberry, Lewis. R. Gale & Lara Killick (2020): Not
throwing away my shot: an analysis of shot features in men’s collegiate water polo, International
Journal of Performance Analysis in Sport, DOI: 10.1080/24748668.2020.1741915