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Saturday, November 17, 2018

A New Statistic: Hammer Factor

Welcome to the new stat of 2018. To be fair, this is a simple calculation using two existing statistics: Hammer Efficiency (or HE) and Steal Defense, otherwise known as SD, though in the early days it was SDE.  These are the two primary stats that Gerry Geurts and Dallas Bittle created over a decade ago to measure a team's performance with hammer.  They also created Force Efficiency (FE) and Steal Efficiency (SE) which measured a teams play without hammer.  Here's a quick refresher on what these actually are:

  • Hammer Efficiency (HE) the percentage of time a team takes 2 or more points with hammer, in ends which are scored. Includes all non-blank ends in which a team has hammer.
  • Force Efficiency (FE) - measures the ability of a team to force their opponent to one point. Calculated by number of ends in which the opponent took 1 point divided by all ends against without hammer where the opponent scores. Stolen and blank ends are not included in the calculation.
  • Steal Efficiency (SE) - the percentage of ends a team is able to steal. It's calculated by dividing ends stolen without hammer by the total ends played without hammer, Blank ends are included.
Steal Defence (SD) - ability to limit the number of stolen ends. Calculated by number of ends stolen against divided by ends with hammer. Blank ends are included

Over the years, HE and SD have provided some indication on whether a team was average, good or great.  Generally, stats without hammer are less of an indicator of success.  

Looking at last season, I grouped teams into several categories, based on World Ranking.  Top 5, Next 5, Top 11 through 20, 21 through 30 and 31 to 50.  Let's first look at without hammer numbers. For men, FE ranged between .48 and .63 with average for each grouping .55, .56 or .57.  The .63 was Gushue, an anomaly at the top, however Tanner Horgan (Rank 23) was .62 and Karsten Sturmay (Rank 48) was .61.  For comparison, Reid Carruthers, Ranked 6th, had an FE of .49.  For all groups SE averaged .25 with only two teams below .22 and two above .28.  Often these non-hammer stats are an indicator of the level of competition.  A top 5 team (like Carruthers) can have a much lower FE than a 35th ranked team who plays against weaker opponents.  In the womens game, FE last year may have been a subtle indicator, with the Top 10 teams averaging .6 while 11 through 50 averaged .55.  SE was similar to the mens, with an average between .25 to .28 for each grouping, with top teams actually being the lower number.  Now on to our new stat...

When digging into these CurlingZone stats, over the years it's become apparent that strength of a team was related to how much they avoided stolen ends.  A low Steal Defence (say, below .20) meant a good team.  When combined with a high Hammer Efficiency (above .45) , indicated likely a great team.  Some teams have differing styles and you could see one team with higher HE but higher SD, and vise versa.

Oddly enough, it was staring at us all along and we only just recently thought to combine these numbers into a formula...  

Hammer Factor = (Hammer Efficiency) - (Steal Defence)

Going back to my team groupings from earlier, when I took this formula and averaged it for each grouping, it jumped off the spreadsheet.  Have a look:
Team World Ranking
(2017-18 Season)
Hammer Factor
Women Hammer Factor 
Top 5
6 to 10
11 to 20
21 to 30
 31 to 50

Now, looking at teams individually, there's still some oddities.  Edin and Gushue are top of the rankings and have the highest HF by far (.33 and .39 respectively).  Howard was .3 at a ranking of 11 and Koe only .24 while being ranked 3rd.  In the womens, Jones and Hasselborg were .28 and .35  while Einarson at 14th had an HF = .27.  But for the most part, Hammer Factor seemed to drop with a teams ranking.

I haven't yet gone backwards to compare past season results and also haven't yet analyzed against W-L records (just rankings).  Perhaps HF could be used in a Bill James Pythagorean Expectation to estimate a team's winning percentage or a Bill James style log5 formula to estimate win probability head-to-head.   More to be done with this new calculation, but for now it's fair to say that the higher the Hammer Factor, the better.

Episode 45 - Robin Wilson

Robin Wilson grew up a fighter.  She was active in supporting social change during the early 1970's and, after earning her business degree, applied for positions in male dominant companies. Her path eventually led to one of the greatest sponsorships in sport.  Robin met Lindsay Davie at the North Shore Winter Club while in their early teens.  Robin, her sister Dawn, Lindsay and Lorraine Bowles would eventually capture the 1976 Macdonald Lassie.  In 1979, they won again and were able to represent Canada at the first ever Women's World Curling Championship.  Robin is the Leadership Director for the Sandra Schmirler Foundation.  Visit to read the incredible stories of babies and parents who are helped by the Foundation.  You can donate online or add a $10 donation to your cell phone bill by texting the word SANDRA to 45678.   

Check out the latest episode of Curling Legends Podcast

Thursday, November 1, 2018

Episode 44 - Pierre Charette

Pierre Charette may have been a little feisty. Regardless of his position for Team Quebec at the Brier (and he played them all) he was intensely focused on trying to win.  During a phenomenal run in the late nineties, he nearly won it all.  Teamed with Guy Hemmings and the front end of Dale Ness and Guy Thibaudeau, Pierre reached two consecutive Brier finals in 1998 and '99.  Pierre reflects on the early days, his Brier experiences, the evolution of the free guard zone and the beginning of the Grand Slams.

Check out the latest episode of Curling Legends Podcast

Thursday, October 18, 2018

Episode 43 - Ron Green

Ron Green grew up in the Toronto curling scene of the 1960s. After a close loss in the Ontario school boys, the opposing skip asked if he would join up the following year.  Ron would go on to curl with Paul Savage for over a decade, with three trips to the Brier and a lifetime of memories.  Ron talks about his early heartbreak, just missing out on a Purple Heart in 1969. Then he explains how the team with Paul, Bob Thomson and Ed Werenich was formed and touches on the battles they had, sometimes with their competition, and sometimes with each other.

Check out the latest episode of Curling Legends Podcast

Thursday, October 4, 2018

Episode 42 - Linda Moore

Linda Moore was always willing to have an open mind.  After losing the Scotties final in 1986, instead of a direct entry to the first ever Olympic Trials, the Moore rink had to participate in the evaluation camp before qualifying to compete.  When told in advance they could be split up as a result, rather than battle the process they went ahead and kept a positive attitude.  The result was a gold medal at the 1988 Olympic Winter Games in Calgary.  Linda reflects on that experience and the lessons that helped get them to that moment.  We cover from Linda's early days as a junior in North Vancouver through to her years as a broadcaster with TSN. Linda shares some Ray Turnbull stories, her thoughts on shooting percentages and explains what led to her departure from the booth.  

Check out the latest episode of Curling Legends Podcast

Thursday, September 20, 2018

Episode 41 - Ian Tetley

Ian Tetley isn't afraid to give his input.  Sometimes a front-end player has to speak out before the wrong shot is called.  According to Ian, his teammates were often too quiet to speak he had to.  His enthusiasm for curling began while watching father Bill win the Brier in 1975.  When he and teammate Pat Perroud got a call to join Al Hackner, he went to his first Brier, and won.  Ian went on to win three World Championships with different skips and left a legacy of double peels (often, it's been said, because he usually missed the first one). We'll discuss the early days in Thunder Bay, the famous Hackner Double in 1985, the first Canadian Olympic Trials, and tales from Toronto during his time playing for Ed Werenich and later Wayne Middaugh.  

Check out the latest episode of Curling Legends Podcast

Friday, September 7, 2018

Episode 40 - Don Bartlett, Part 2

In Part 2 of my conversation with Don Bartlett, we cover the boycott years, dig deeper into the Ferbey rivalry and reflect on his Olympic experiences.  Don will also talk runback strategy, handling emotions in big moments and eventually weigh in on the greatest teams and players of past generations.

Check out the latest episode of Curling Legends Podcast