lol! aw... It's even worse when someone makes a judgment on something they have no practical experience at. Might as well sit up in the observation area watching brain surgery making judgement on what the surgeon is doing when you've never even taken a first aid class.
So, understanding stats isn't the issue... I just didn't know what the terminology for each data point was. I worked in an engineering dept for more than a decade dealing a lot of statistical analysis as it related to design verification test results.... Not my favorite thing but again I have real world expereince with it...
If you know stats so well, then what is your problem with sample size? That's like the first thing you learn in stats, don't trust a small sample size. Yet you insist that his production in the playoffs is important and his production during the regular season wasn't, even though one is a vastly larger sample size.
So what is the equation that generates those numbers? What are the tolerances that are acceptable? I notice you had no answer for that when I asked previously. Truth is you don't know. When boyle is at -5.5 what does that translate to? Is he spending his entire shift in his own zone? Quoting advanced stats is just a way for those with no practical real life experience to try and support their opinions. Doesn't make those that do it right. There is something to be learned from the stats but it isn't the whole story and it takes an experienced eye to determine when the stats are worthwhile and when they should be thrown out.
I don't recall you asking, but I assure you that I do know.
The equation that generates those numbers? I told you, it's shot attempt differential. Shot attempts are shots on goal, goals, missed shots, and blocked shots. Corsi is shot attempt differential per 60 minutes of ice time. A -5.5 ranking means that on average, in 60 minutes of even strength ice time, Boyle has a -5.5 shot attempt differential, which means that teams take 5.5 more shot attempts in that time while Boyle is on the ice than Boyle and his teammates do. That could mean that Boyle/teammates take 40 shot attempts and opponents take 45.5 shot attempts per 60, or that Boyle/teammates take 5 shot attempts and opponents take 10.5. If the former, he would be a high-event player (which he is), if the latter, he'd be a low-event player. Now, guys like Scott Hannan are low event players. That means that he is decent at preventing attempts, but not good at creating attempts either. This is why he is called "good defensively". Guys like Dan Boyle or Matt Irwin are what you call high-event. They give up a lot in their own end, but they also create a lot in the opponent's end.
Now, you can't know who's a high-event player and who's a low-event player just by looking at Corsi. Corsi measures differential, basically who does their job best. Hannan may give up less scoring opportunities than Irwin, but Irwin creates enough in the opponent's end that he ends up with a positive differential, while Hannan blows so much in the offensive end that he can't make up for what shot attempts he yields. So while Hannan is "better defensively" than Irwin, Irwin is the more effective player overall and contributes positively to winning.
Truth is, when talking about athletics, statistics are a very small part. More so for the fans probably... and the scouts to a certain degree. If advanced stats were all that is necessary they wouldn't have to travel around watching these kids play. Once you have the players in the room it's different. Kevin Constantine didn't use any advanced stats to determine which goalie would start each game against the Calgary flames back in 94-95. It was an experienced eye. Psychology is infinitely more important in sports than a math degree...
In the end, the experienced eye is more valuable than all the advanced stats in the world. The sharks employ people who have spent a life time playing and analyzing the sport and it's athletes and they are much more capable of that than anyone here at doing so. So it's largely meaningless and intellectually disingenuous to say that it looks like his play is declining because of an eye test.
One stat that used in conjunction with all these others that is interesting to me is that Boyle finished as a plus player in the regular season. Right behind MEV and Stuart. Ahead of Patty...
Extrapolated out it would have been right inline with his typical rating for the season.
In the playoffs he did finish -3 which isn't great but his value on the PP outweighed that IMO. Irwin finished even worse at -4 and Couture finished a team worse -6. Finishing -6 in only 11 games is frickin atrocious... or horrendous as you put it... It's funny you place so much importance on Boyle's playoff stats... extrapolated out he's looking at a 60 point season... In both cases, regular season and playoffs... Boyle logged the most ice time of anyone on the team who wasn't a goaltender..
Even in his best offensive seasons Boyle barely finishes as a plus player. Looks like his best recently was +10. Jeez he had a -29 in like 40 games right before he came to the sharks... obviously he should have retired then...
I'm not sure why you all of a sudden brought +/- into the discussion, but you should know I put absolutely no stock into that stat and think it's garbage.
But you should be aware that many NHL teams use advanced stats, including our very own San Jose Sharks. The Canucks, Penguins, and I think Bruins are a couple others that do. New Columbus GM Jarmo Kekalainen is a fan of advanced stats. And advanced stats were actually thought up by an NHL player-turned-coach, Jim Corsi:
http://www.sportingnews.com/nhl/story/2013-04-23/jim-corsi-hockey-definition-nhl-advanced-stats-primer-behind-the-net-fenwick-pdo
I hope I helped you to understand possession stats. Obviously they aren't an end-all be-all to hockey, but they're absolutely a great part of analysis.