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One of the more common measurements used in hockey analytics is known as Goals Versus Threshold -- an algorithm created by Tom Awad that assigns player value, in goals, above what a replacement player would have contributed.
Awad's studies are based on the rationale that hockey is a game of scoring opportunity creation and prevention -- those who create the most positive margins are generally the most productive players. And, vice versa.
The statistic also accounts for the variance in productivity on a position-to-position basis. The four functions of each player's total output includes offense(goals created), defense(goals prevented), goaltending(if applicable), and performance in the shootout(denoted hereafter as "sGVT") -- a necessity since the past lockout, as a marker in the skills competition does
directly modify winning percentage. The functions are also weighted based on the position -- forwards are more responsible for goals-created, and defenders are more responsible for goals-prevented. More on the weights can be found
here.
Below, Awad discusses the five key components or fundamental characteristics of GVT -- something that must be considered prior to statistical review:
1.) GVT is measured in goals. This makes it a convenient unit that hockey fans are already comfortable with.
2.) GVT compares hockey players of all positions and over any period of time.
3.) GVT only uses statistics that lead directly to goals. You cannot incorporate goaltender wins into GVT, because they are not a measurement of goals prevented. However, if you can rationally explain what are the odds of a faceoff win (or loss) leading to a goal or goal against, it would be possible to incorporate faceoff wins and losses into GVT, though I have not done so.
4.) GVT has built-in accounting. The sum of player GVTs on a team equals that team's GVT plus the replacement level. This is essential, as player statistics often come with caveats. Player X scored 43 goals, but he doesn't play defense and his team isn't good. This makes it much easier to measure "how good would this team be replacing player A with player B?" It is also essential in that player success is correlated with team success, which after all is the entire point of the sport.
5.) GVT automatically normalizes for the strength of the league. When looking at player statistics from different eras or different leagues, it is often difficult to know if a player was good or not. For example, for the last few years in the Czech Extraliga, a save percentage of 0.920 has been average or below average, while in the NHL today a save percentage of 0.920 is pretty good, and in the NHL 20 years ago it was unheard of. Similarly, a 50-goal season in 1982 was less impressive than a 40-goal season today. GVT takes all of this into account, giving you a single number that doesn't need any further interpretation.
Let's take a look at the returning Ottawa Senators and how they fared last season:
Some thoughts below.
-- Erik Karlsson finished twelfth overall in the National Hockey League in GVT, sandwiched between the likes of Ilya Kovalchuk, Cory Schneider on one end -- Jaroslav Halak and Patrice Bergon on the other. When you consider how dominant the goaltending position was this season(seven of the eleven players that finished above EK65 played G), Karlsson at twelve is pretty damn impressive. His Norris Trophy comparables in Zdeno Chara(+18.0) and Shea Weber(+15.4) finished 27th and 47th, respectively. Both possessed very strong dGVT splits, but couldn't touch Karlsson's impact on the offensive end.
-- Jason Spezza and Daniel Alfredsson finished as the top two forwards on the team, and both finished inside of the top-forty among all National Hockey League skaters. For Spezza, that's pretty obvious -- the eighty-four point campaign he put on was good enough for a fourth-place finish among point-scorers. Alfredsson, though, is pretty intriguing, and speaks a ton about his two-way play and possession game in general. In an injury-shortened season where head trauma was a real issue, Alfredsson was still able to perform at the highest of levels, finishing just two spots behind all-world sniper Phil Kessel.
-- Both are in incredibly limited sample sizes, but it's impossible to ignore the variance between Robin Lehner and Ben Bishop in their brief stints. Bishop looked a bit shaky, and the numbers aren't very supportive either; Lehner was dominant stepping into a relief role, and hopefully that continues to translate as he progresses through his professional career.
-- Know how you had a bad season? Peter Regin played ten games and almost posted a better GVT than fifty-six game man Bobby Butler. With Butler, the 'sink or swim' approach used by Paul MacLean was quite fair, but Butler went down like the S.S. Minnow. Posting such a poor GVT certainly doesn't speak about his quality above replacement players -- there's hardly a difference right now, and considering the alternatives at Paul MacLean's disposal internally, his future is pretty cloudy.
-- One angle worth watching is the Erik Condra v. Colin greening battle for TOI on the wing. Greening offers far more offensively; Condra's nicely transitioning into a shutdown role of sorts. They may be developed for entirely different roles on the team, but there's only eight wing positions in an NHL starting lineup, and Condra could be permanently relegated into the bottom-six in Paul MacLean's puck-possession system. Stopping goals, he excels; scoring 'em, not so much. Don't be surprised if the coaching staff shows more favor to Greening next season and in the future, even though both had comparable seasons in 2011-2012.
-- Of the three names coming into the fray from other clubs last season, none were especially appealing in the GVT department. Latendresse and Lundin were obviously curtailed by injury-plauged seasons, and their numbers (+2.5 GVT, 439th NHL // +0.7 GVT, 608th NHL) suffered, respectively.
Marc Methot, in his shortened season(46 GP), didn't fare much better. His 606th finish in the NHL (+0.7 GVT) was directly comparable to Roman Horak and Taylor Pyatt. Hopefully, a change in scenery -- and, return to health -- will boost his numbers.
-- A final note: Alex Auld finished in the bottom ten of the entire National Hockey League, with a GVT of -7.5 -- mere decimal points ahead of James Reimer and Brent Johnson, if that helps paint a more descriptive picture.
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Thanks for reading!
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