With all of the advances in hockey statistics, goaltending performance is still the most difficult position to accurately measure and predict. If you don't believe me, Travis Yost from TSN just wrote an article that illustrates this point quite nicely. However, the good folks over at War on Ice have done a good job so far at trying to examine goal tending performance by focusing on shot location. We will be referring to their high, med, and low zones during this article. If you are interested in learning more about how they came up with these zones you should check out this article on their website. In this part of the series we are going to look at the decision to pick Jake Allen over Elliott, and then compare Allen's performance during the regular season compared to what happened in the playoffs. As usual, unless specifically stated, all data is 5v5.
Was starting Allen in the playoffs the right choice?
Taking a look at the basic trend line for save percentage by game during the season, it is clear that Brian Elliott was on a downward trend. It doesn't matter which way you look at the trend, his save percentage in the latter half of the season was not as good as during the first half of the season. I looked at just the trend line (that you see below). I looked at a cumulative trend line, moving average trend line, and War on Ice's adjusted save percentage for goalies. They all went in the same direction...down. Meanwhile Jake Allen's save percentage was trending ever so slightly upwards during the latter part of the Blues' season. So from that standpoint, you can understand why Hitchcock made the choice to start Allen instead of Elliott in the playoffs.
However, if you dig a little deeper using the stats provided by War on Ice, you can start to provide some explanation as to why Elliott was "struggling" late in the season. The second tab below shows the percentage of shots over the course of the season that each goalie faced from each of the three zones. For instance, if you look at the last data point for Elliott (the game on 4/11/2015) 12.5% of the shots he faced originated in the high danger zone, 12.5% of the shots he faced came from the medium danger zone, and the remainder of the shots (12 out of the 16 shots total he faced or 75%) came from low danger zones on the ice. What I find interesting about this chart is that the percentage of shots originating from the high danger zone actually trended upwards over the course of the season while Allen's trended downward. While both Elliott's and Allen's high danger zone save percentage trended downward, Elliott's trend was much more pronounced. However, as the percentage of shots from the medium zone trended downward for Elliott, so to did his save percentage, while Allen's save percentage trended upward for that same zone while the shots he faced remained steady. Finally Allen's low danger shots trended upwards while his save percentage trended flat throughout the season.
So did Hitchcock make the right call in starting Jake over Brian? Both their normal and adjusted save percentages say yes. However, my initial reaction to seeing Elliott facing more shots from high danger areas made me feel that this could have been a plausible explanation for his downward trend, and one that he is helpless to prevent. But the trend in his save percentage for med zone shots seems possibly suggest that Allen might have been the better choice.
Breaking down Allen's playoff performance
During both the regular and post season, the percentage of shots he faced from each of the zones is exactly as you would expect; less shots from the high danger zones and more shots from the low danger zones. Comparing the regular season shots to the playoffs didn't see much of a change in the number of shots he faced from the high zone. However, he did face more shots from the medium and less from the low than he did during the course of the season.
His save percentages also differed for each zone between the regular season and the playoffs. He actually had a higher save percentage for high danger shots in the playoffs than he did in regular season. As a result the share of goals scored on him from the danger zone also dropped between the regular season and playoffs. He saw more shots from the med zone in the playoffs than in the regular season, and his save percentage remained the same between regular season and playoffs. Consequently, more goals were scored on Jake from the medium zone during the playoffs than during the regular season. Is this something you can blame on Jake? Probably not. It wasn't that he was stopping less of the shots he faced, it was a matter of him facing more shots and thus more goals were being scored. Could we lay the blame on the defense? Possibly. Finally, the percentage of shots that Allen faced from low danger zones decreased in the playoffs, however so did his save percentage. This translated to an increase in the percentage of low zone goals being scored when compared to regular season. This was problematic and we can definitely point to Allen giving up these low zone goals as a contributing factor to the Blue's playoff demise last season.
So was goal tending to blame?
Based purely on the numbers, I can see why Hitchcock chose to start Allen in the playoffs instead of Elliott. However, my gut says Elliott should have at least been given a chance but put on a short leash. First signs of trouble you put in Allen. However, Hitchcock chose to play Allen all the way through even after that dreadful goal when Hitch kept Allen in the game only to have Allen give up a second bad goal right after Hitch justified his decision. While Allen seemed to hold his own during the regular season, his giving up goals from shots that originated in low danger shot areas was a problem. Can you hang the Blues' inability to move past the first round on Allen's goaltending performance? I don't think so. It was one of several problems I've tried to document during this four part series, but it was not THE problem that caused the Blues to end their season early.
One article left in this series, and that is the final conclusion trying to wrap up all four parts of this series. I will try to incorporate any thoughts and questions you all have submitted in the comments of the previous articles, as well as this one. I look forward to reading your thoughts.