The League of Extraordinary Statisticians: The Defensemen

The League of Extraordinary Statisticians (LOES) is a weekly forum bringing together top analytical minds in the hockey world to answer a variety of questions that straddle the line between stats analysis and something you might hear floating around section 304.  They have agreed to answer these questions in a few paragraphs or less, and with minimal formulae.  Because this is a forum, we'd encourage you to use the comments section to answer the questions yourselves, or to discuss or debate the answers given.

The LOES is not meant to represent the entire of the hockey stats community.  There are a number of people that either were too busy or too difficult to contact for the purposes of the forum.

You know the guys I'm talking about: Adam Foote, Greg Zanon, Colin White...your quintessential "defensive defensemen" are the players that don't jump out to the casual fan, and for good reason.  You'll rarely see them in the box score, and they rarely attain any type of celebrity (although Jeff Beukeboom was on a pretty great SportsCenter commercial,  and we all know that Craig Ludwig transcends definition).  Yet this week I wanted to give them a chance for redemption at the hands of the LOES, because for as much as we notice the highlight-reel goals and end to end rushes, we also tend to ignore the battered shinpads and technical savvy that undeniably means something to the outcome of a game.

But will they be redeemed?  One of the bigger shortcomings in the hockey stats analysis world is that there are few metrics that appreciate defensive defensemen to the same level of their forward-minded defensive counterparts.  Alan Ryder's Player Contributions is one of these few (Tom Awad's GVT isn't too bad, either); otherwise, the norm has been that most hockey metrics tell use quite a bit about offensive performance and talent, but not much about the defensive side.  Maybe in the future that will change (fingers crossed for BZS), but for now let's see what the LOES can do for us.

The question for this week is: Is a defensive defenseman capable of matching the value of an offensive defenseman? How might this be expressed statistically?

It is easy for the value of a defensive defenseman to match the value of an offensive defenseman, but it is hard for him to match the value of a two-way defenseman.  Top defensemen can contribute at even-strength, on the power-play and on the penalty-kill; a defensive defenseman, even an elite one like Willie Mitchell or Greg Zanon, is handicapped by his inability to contribute on the PP. On the other hand, one-way offensive defensemen, like Tobias Enstrom or Alex Goligoski, are limited by the opposite problem. Best of all is someone who can contribute in all situations: Nicklas Lidstrom, Zdeno Chara or Duncan Keith, but also Marc Staal, Brent Seabrook and even Mike Green.

Luckily for defensive defensemen, at even-strength defensive skills are more important for a defenseman than offensive skills. To find a top defensive defenseman, the 3 most important metrics are even-strength ice time, PK ice time and QualComp. A fourth is Corsi adjusted for Zone Starts, QualComp and QualTeam (DeltaSOT or something similar).

- Tom Awad, Hockey Prospectus

Norris Trophy voters have opined on this - not since Rod Langway has a "defensive defenseman" been selected as the NHL's top blueliner.  I concur with the general thinking.  It is hard to imagine that a defence-only stud can be worth as much to a team as a defender who combines well-above-average offense with solid defensive play.

 

I address this question directly in Player Contribution (PC).  A summary of the logic is: defensemen account for a little under 25% of offense.  This is about what point totals tell us, although I use a more sophisticated 'Goals Created' formula to get there.  They record a little over 40% of ice time, picking up relative ice time while short-handed and four-on-four but giving back to a fourth forward on the power play.  Per minute of play, forwards generate a little over twice the offense of defensemen.  By inference (for the sake of brevity, no math here), about 56% of defence is attributable to defensemen.  This means that defensemen, on average, are about 30% offense / 70% defence.  But the differences in individual performance on offense are so much larger than the differences on defence that a defence-only player can't compete.

 

Let's compare (from the 2009-10 season) Greg Zanon (MIN) and Colin White (NJD) to Nicklas Lidstrom (DET) and Drew Doughty (LA).  I figure that the pairing of Zanon and White contributed an average of 6.0 points to team success through their defence.  I had them ranked as the 6th and 7th top Defensive Contributions of last season.  I figure that the pairing of Lidstrom and Doughty contributed an average of 6.1 points to team success through their defence.  I had them ranked as the 3rd and 9th top Defensive Contributions of last season.  So these four players were among the very best in their own zone.  But here is the offensive story:

 

Player	G	A	Pts
Zanon	2	13	15
White	2	10	12
Lidstrom	9	40	49
Doughty	16	43	59

No contest.  Zanon's overall (offense too) contribution was more like that of teammate Marek Zidlicky.  White's overall contribution was less like Drew Doughty and more like that of Jack Johnson.

- Alan Ryder, Hockey Analytics

 

In principle, yes a defensive player can have the same value as an offensive player.  This is true for defencemen or any other position.  It would occur if the number of goals prevented by the defensive player (and hence wins they are worth) is greater than the number of goals created by the offensive player.  In real life, players have offensive and defensive value and many of the best defencemen of their eras are both offensively and defensively talented.  These include Bobby Orr, Doug Harvey, Eddie Shore, Nicklas Lidstrom, Ray Bourque, Denis Potvin and Larry Robinson, so it is a largely theoretical question.  The best defencemen qualify as both offensive and defensive defencemen.

- Greg Ballentine, The Puck Stops Here at Kukla's Korner

Of course!  A goal prevented is just as valuable as a goal generated.  In fact, in the salary cap era you need to find bargains (players that produce more than their market value) and typically offensive-minded defensemen are far more likely to be overpaid than the defensive-minded.  
 
Statistically you could use either GVT or PC at a high level, both of which are statistics that summarize all of a player's contributions into one statistic, allowing you to compare players in different roles.  To convert that measurement into a value, you could either use GVS, or PCValue ($56,800 per point of PC).
 
Last season, for example, the best values among defensemen were:

GVS: Tyler Myers, Ian White, Andy Greene, Drew Doughty, Keith Yandle, Marc Staal, Mark Giordano, Mike Green, Duncan Keith, and Marc-Andre Bergeron.  

PCValue: Andy Greene, Duncan Keith, Keith Yandle, Tyler Myers, Mark Giordano, Ian White, Marc Staal, Jeff Schultz, Niklas Hjalmarsson, and Kris Russell.
 
See?  Lots of defensive-minded defensemen, especially when using the more detailed PC approach.  You can get elite defensive blueliners a lot cheaper than what it costs you for the offensive-minded.

- Rob Vollman, Hockey Prospectus

Absolutely. Preventing goals, preventing shots, playing tough minutes, and playing against top competition is absolutely valuable, as valuable as those who score goals, generate shots, and play soft minutes against soft competition. 

Obviously, not every offensive defenseman is worth every defensive defenseman. This is inherently obvious, just like how Manny Malhotra is not as valuable as Steven Stamkos. But to argue that Niklas Hjalmarsson is not as valuable as Brian Campbell (cap hit aside), or that Zach Bogosian isn't as valuable as Dustin Byfuglien is ignoring the guys who play defense so others can play offense. Just on the Flyers, Braydon Coburn matches the value of Matt Carle, despite Coburn being more defensive-minded than Carle.

How to show this statistically? GVT seems to be the best way currently. Unfortunately, DGVT fails to properly credit individuals for their defensive contributions. If the metric could shift from team-based metrics (like time on ice and team shots against) into individual metrics (including zone start, CorsiRel, and Corsi Rel QoC), maybe we could start to properly quantify defensive contributions. Until then, defense in hockey will be similar to defense in baseball until recently.

- Geoff Detweiler, Broad Street Hockey

We have a bit of a definition problem.  Who's a defensive defenseman?  Is Marc Staal (19 points) a defensive defenseman?  Paul Martin? Dan Hamhuis?  Henrik Tallinder?  Robyn Regehr? Chris Phillips?  Because those guys have a very well-established value and they're highly-compensated.  You could give them "Dustin Byfuglien ice-time" and turn them into 50-point players, but that's not the most effective use of them.  Given how easy it is to find PP point men (ie - a 4th forward), I think the question is really whether an offense-first defenseman can match the value of a defensive defenseman.

- Gabe Desjardins, behindthenet.ca and, of course, Behind the Net

Though maybe not on the level with Andy Dufresne's redemption, it's a redemption nonetheless.  I think that the tide has turned a bit in recent years for the defensive defenseman, as we've seen players like Dennis Seidenberg and Anton Volchenkov fetch respectable figures on the open market ($3 million-plus), but even so these figures are the lower-end for defensemen with comparable offense-to-their defense value.

Do you think that defensive defensemen are gradually catching up to the level of appreciation reserved for offensive defensemen?  How do you determine the quality of a defensive defenseman?  Or just as important (as Gabe points out), how do you define a defensive defenseman?  Though not covered by me or the respondents, one thing that comes to mind is hitting.  Does a defenseman's amount and power of hitting muddy the waters on what a defensive defenseman's responsibilities are and what quality defense looks like?  I think a common misconception is that a defenseman that hits a lot is inherently a good defender, and that's not necessarily the case.