Wednesday, 17 September 2014

Shot Suppression Is The Name Of The Game

As the “Summer of Analytics” wraps up and various NHL camps get underway, there is a palpable urgency apparent from some NHL front offices to find the key to success by expanding their analytics departments. The task teams are currently undertaking is to identify their strengths and weaknesses by conventional and progressive means. Once they do this, they can then come up with a plan to exploit their strengths and improve the areas of weakness.

While there is no secret weapon or magic trick that will suddenly make a good team from a bad team, there are some team strengths that are more important to success than others. In looking at successful teams over the past several seasons, one such strength stands out from the rest: Shot suppression.

Shot suppression is a fairly basic concept, but because it is not as exciting as a high powered offense or as easy to identify as say an excellent penalty kill, it is not often discussed during broadcasts or major media analysis shows. Shot suppression is one of the true measures of the quality of a team’s defensive structure and systems. Even in analytics, this component of team play can be overlooked when we use percentages such as CF% (Corsi For) or FF% (Fenwick For). Percentages are terrific and useful for many things, but one of their shortcomings is that they mask Event Rates.

Event Rates are often expressed as whatever metric is being used “Per 20” or “Per 60”. To understand how aggressive an offense is, CF or FF rates are very useful. For example, the San Jose Sharks had the highest CF60 in the league at Score Close last season with mark of 63.6 and were third in the league in FF% (most popular team possession measurement tool) at 54.9%. The Ottawa Senators were second in the league in CF60 with a rate of 63.2, but were twelfth in the league in FF% at 50.8%.

When the CA and FA rates are added into the mix, we can see which teams allow more shots than others. When used in combination with the team’s CF and FF marks we get a picture of a team’s event rates.



You will note that the best or most successful teams in the league are not at either extreme in terms of event rates. They are not super low event like the New Jersey Devils nor are they super high event like the Ottawa Senators. Teams with very low event rates both in terms of shots for and shots against often struggle to produce enough offense to consistently win games. This was obvious last season, when Devil’s goalie Cory Schneider played very well but was consistently losing games because of a lack of offensive support. Likewise, teams with very high event rates in shots for and against tend to score quite a bit, but they also tend to give up a lot of goals.

The real question is: what is most important? Shot suppression or a prolific offense? Looking back over the past several seasons at teams that were successful both during the regular season and the playoffs may lead us to an answer.


2007-08


In the plot above, the FF60 and FA60 for each team are shown as a deviation from average that season. Teams with a lower than average FF60 are left of the vertical axis and those higher than average are to the right. Teams with lower than average FA60 are below the horizontal axis and those higher than average are above it. The best possible mix of both prolific shooting and effective shot suppression is shown in the teams located in the bottom right quadrant of the graph.

During the 2007-08 regular season, the Detroit Red Wings had the highest FF60 (Fenwick For Per 60) rate of any team in the league. The Red Wings also boasted the lowest FA60 (Fenwick Against Per 60) rate in the league.

When we then look at which teams made the playoffs, it gets very interesting.



 The teams that disappear from the graph are mostly those from the upper right quadrant and upper left quadrant. These were the teams with higher than average FA60 rates throughout the season. The teams that suppressed shots well made the playoffs for the most part. Montreal, Pittsburgh and Philadelphia were the teams with the highest FA60 rates to make the playoffs in the 2007-08 season.
Detroit was obviously the best 5 on 5 team going into the playoffs based upon their FF60 and FA60 marks, so how did Pittsburgh, with its high FA60 and relatively low FF60 make it to the Stanley Cup Final?

First, Pittsburgh’s Sv% (Save Percentage) in the playoffs was 93.8% at 5v5, good for the second highest Sv% during the playoffs. Second, the team’s sh% (shooting percentage) through the playoffs was 9.04%, which although not all that high, when combined with their Sv% produced a PDO of 102.84, second highest in the playoffs. Third, Pittsburgh’s GF60 (Goals For Per 60) was 2.6, good enough to tie for second in the playoffs. So, essentially, Pittsburgh ramped up their play during the playoffs and overcame their lack luster FA60 & FF60 from the regular season, until they ran into Detroit, which also had a fairly high playoff PDO (102.3) and continued to suppress shots at a high rate. 

2008-09


Again, we find Detroit with the best overall showing in terms of Fenwick event rates during the regular season. San Jose and Washington also remained in the bottom right quadrant during the 2008-09 season. Chicago showed a significant improvement in both FF60 and FA60. Pittsburgh dramatically improved their FA60 as well.


Again, the teams that made the playoffs tended to be those with better FA60 marks than the rest of the league. Pittsburgh’s goaltending also stands out as having been significantly better than the league average while Detroit’s was a bit short of that mark. Pittsburgh had a very high GF60 (2.8) during the playoffs and the third lowest SA60 (Shots Against Per 60) which combined to help them outlast Detroit’s sky high playoff PDO (103.79) and second best SA60 mark.

2009-10


During the 2009-10 regular season, Chicago not only had by far the most impressive FA60 but came close to having the best FF60 as well. Pittsburgh improved its FF60 during the season while staying about the same in terms of FA60. This is the beginning of New Jersey’s progression from a team that suppresses shots pretty well and maintains a decent FF60 to a team that leads the way in terms of low event hockey. The Devils took a dramatic step back in their FF60 and have continued to do so ever since.


Again, the teams showing the better shot suppression rates made the playoffs. It is curious that we also see a trend developing wherein teams with good shot suppression rates seem better equipped to overcome goaltending struggles throughout the regular season as well. Chicago won the Stanley Cup defeating a much improved (in terms of FA60) Philadelphia team.

2010-11


New Jersey claimed its shot suppressing crown during the 2010-11 season and has been loath to give it up since. This season also showed more disparity among teams that seemed to get it together in terms of suppressing shots while enhancing their offensive structure. The lower right quadrant got pretty crowded.


 Good shot suppression teams once again took most of the playoff spots, while teams that struggled a bit in the FA60 category rode good FF60 and goaltending into the playoffs. Only Anaheim initially presents as a real outlier here but featured Corey Perry’s 50 goal season (98 points) as well as strong offensive showings from Bobby Ryan (34 goals, 71 points) and Teemu Selanne (31 goals, 80 points), not to mention Ryan Getzlaf’s 57 assists. Anaheim also had an extremely effective Power Play during the 2010-11 season. Despite all of this fire power, when the playoffs came, they had problems in goal and their less than healthy systems failed them.

Boston had the highest playoff PDO (103.76) with Vancouver (102.33) finishing fourth in that category. Both teams had simply excellent 5v5 goaltending performances, but Boston’s 94.8% mark simply proved too much.

2011-12


New Jersey continued its quest to stop hockey from having shot events either for or against during the 2011-12 season. Detroit regained some of its prior form with a marked improvement in FA60. Pittsburgh again improved its systems ending the season with the best FF60 as well as a very good FA60. St. Louis also improved upon their rates from the previous few seasons.



Adding in the Sv% when looking only at the playoff teams, makes things a bit clearer. New Jersey’s Sv% was just the slightest bit below average, but they simply did not give up shots to their opponents. Pittsburgh had very nice numbers but their Sv% was far below league average. The team exited the playoffs last in PDO with a mark of 95.81. Detroit had the second lowest at 96.77, with Philadelphia, St. Louis and Chicago close on their heels.

New Jersey had a playoff PDO of 103.2 while the L.A. Kings finished at 103.57. In the Stanley Cup Final, the Kings had a Sv% of 94.7%, while the Devils goaltending faltered to 90.0%.

2012-13


New Jersey, Chicago, St. Louis and L.A. were again determined not to give up shots to their opponents during the 2012-13 lockout shortened regular season. Chicago and L.A. managed to keep their FF60 in positive territory in relation to the league average. Boston and Carolina had the highest FF60 marks but Boston was largely superior in FA60 at the same time.



Once again, shot suppression continued to be the name of the game when it came to making the playoffs, but Sv% in that shortened season also played an important role. The teams with struggling goalies were able to overcome those troubles by keeping shots against low. The teams that had higher FA60 marks also had goaltending above the league average.

Coach Randy Carlyle, just as he did in 2010-11, was determined to provide an outlier on this graph, with Toronto making the playoffs despite a poor FA60. At least this time, the goaltending was above average thereby keeping the general principles of these findings consistent.

It is no surprise then that the playoff teams holding the best FA60 and FF60 marks ended up playing one another in a Stanley Cup Final many feel to have been one of the most evenly matched and entertaining in recent years. Both Chicago and Boston had very good PDO in the playoffs at 102.1 and 103.2 respectively.

2013-14


The usual suspects from a defensive systems perspective again showed their shot suppression mettle during the 2013-14 regular season. New Jersey, Chicago, L.A. and St. Louis led the way in FA60 with L.A. also making a run at the FF60 regular season crown. Ottawa stands out as the wildest event rate team having the highest FF60 but also the fourth highest FA60. They certainly could not be confused with a boring team during the 2013-14 season.


As we look at the playoffs, we once again see that the teams in the lower half of the graph had a better shot at making the playoffs. With the exception of Philadelphia, the teams with the highest FA60 marks also had goaltending far above average. During the 2013-14 season, the playoff teams with the best FA60 (Chicago) and FF60 (LAK) met in the Western Conference Final instead of the Stanley Cup Final.

The New York Rangers turned their 101.9 playoff PDO into a Stanley Cup Final appearance, but L.A.’s defensive system proved to be too much. L.A. dominated the series and turned an impressive regular season into a championship once again.

Throughout the last several seasons, teams skilled in shot suppression have made the playoffs with far more regularity than teams having a higher than average FA60. Since 2007-08, 112 teams have participated in the playoffs. Of those 112 teams, only 11 have made the playoffs with a FA60 above the league average on the season and without the benefit of goaltending above the league average. Of those 11 teams, without good shot suppression and without above average goaltending, only 2 have made it past the first round of the playoffs.

In 2010-11, the Detroit Red Wings had an FA60 that was 1.29 above the average for the league with a Sv% that was 0.192% below league average. The won their first round playoff match up, but lost in the second round of the playoffs to the San Jose Sharks. The really interesting thing about this is that the Red Wings had the highest FF60 of all teams that season to make the playoffs. San Jose was tied for the second highest FF60, had FA60 2.21 below league average and a Sv% 0.828 above league average.

The only other team to get past the first round of the playoffs with a higher than average FA60 and below average Sv% was the Philadelphia Flyers in 2011-12. Philadelphia finished the season with an FA60 0.12 above league average and a Sv% 0.65 below league average. The team had an FF60 1.95 above league average. They were eliminated in the second round of the playoffs by eventual Stanley Cup Finalist New Jersey Devils.

Since 2007-08, the only team to win the Stanley Cup after finishing the regular season with an FA60 above the league average was the 2010-11 Boston Bruins. The Bruins entered the playoffs 1.09 higher in FA60 than the league average; however, the team’s FF60 was 2.39 above average and their Sv% was an astounding 1.318% above the league average. Boston had a Sv% in each of their playoff series of 92.6%, 95.3% (with team sh% of 15.5%), 91.6% (team sh% of 10.4% versus opponent Sv% of 90.0%) leading up to the Stanley Cup Final. In the SCF, Boston’s Sv% was 96.7%. The team’s sh% was 10.2% while their opponents struggled mightily to score. It seems safe to say that despite being a bit above the average in giving up shots against, Boston’s main source of success in the playoffs that season came from the stellar performance of their goaltender.

The moral of this story is simple. If teams want to make the playoffs, they have a better chance of doing so if they are skilled at shot suppression. If a team ends up a bit above the league average in giving up shots against, their goaltending needs to be very good to get them through. Once the playoffs start, it takes an amazing goalie performance to carry a team less adept at shot suppression through to the Stanley Cup Final and on to a victory parade.


In addition to contributions here at Progressive Hockey, Jen LC is on Twitter @RegressedPDO and writes about hockey with an analytics focus at www.thecommittedindian.com. She can be reached on Twitter or by email regressedpdo at gmail dot com. 

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