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Friday, May 15, 2020

Ruling the Final End

There's been plenty of discussion recently on whether the WCF should shorten all events from 10 ends down to 8. But there is another consideration that's floating in the curling ether that could perhaps more dramatically alter the sport. This rule was used in the now defunct Elite 10 match play format for all ends and some people pondered its use in "regular" curling as a change for possibly all ends or maybe just the final end (or extra end). The Champions Cup adopted this version of the rule for last year and would have used it again this spring if not for the COVID-19 pandemic.

The rule allows for a lead rock placed on the centre line to not only be in the free guard zone, but to be considered frozen in place on that line and unable to be moved by the opponent until the 6th rock of the end. Rather than play a tick shot and move the centre guard away from play, a team tied with hammer would now be forced to another strategy, invariably putting more rocks in play during the end. The reason this rule is being discussed stems from the increasing proficiency with which teams can execute the tick shot. With continued improvement in skill the shot will become so routine a team without hammer will never be able to put pressure on the opposition and a tied game in the final end will become an anti-climactic victory for the team with hammer. The fear is dramatic final ends will increasingly become routine, too repetitive and lower competitive balance.

The reasons for tweaking curling rules over the past 25 plus years has been to balance a fair test of competition with an entertaining contest that keeps fans interested in the outcome. When ice conditions, push brooms and skill level surpassed the point at which traditional rules were entertaining, the sport had to shift to a new rule (Free Guard Zone) in order to keep its appeal and continue to grow globally. I sometimes ponder if ice conditions had not improved and mixing broom use was allowed during a game (as seen in the 1980s and early 90s) everyone might have held off on these new rules (though probably not) and the game could have remained entertaining to fans, if partly due to the odd fight between teams over an alleged 7-up dipped corn broom.

But here we are. Three rock (in Canada) went to 4 rock and now 5 rock and it appears we have a great game that is enjoyed by many and growing around the globe. So, the first question to be asked is why change?  Firstly, I don't want to disparage the consideration. It is good practice to continuously consider how change can improve a sport. The three-point line, changes to the hand-check rules in the NBA and various NFL rules starting from the mid-70s in order to increase passing, have changed these sports for the better and improved their entertainment value. Any debate on the dreaded neutral zone trap in the NHL has hopefully disappeared. Sometimes mistakes are made (see late 90s NBA shorter three-point line), but in general I applaud sports attempting to improve as its athletes, fans and conditions change. In the case for curling, the part of my brain that yells at kids to “get off my lawn” thinks the sport has experienced so much change in the last 30 years that we've become addicted to thinking it constantly needs altering for the sake of change rather than just enjoying it for what it is. If people spent more time on growing the sport by getting more people to "play it", rather than focus ad nauseum on changes to make to it, in their perspective, "better", the sport would be further ahead. Instead of arguing for further on ice changes, could we possibly improve the arena and live viewing experience and get more butts in seats?

Perhaps part of this behaviour is simply because curling has changed so much over the past few decades that we all feel a need to constantly tweak and alter its form out of habit. We live in a sports world where the audience doesn’t simply watch games but derive pleasure in becoming an agent, general manager or owner while tweeting from their couch. In a culture of daily fantasy sports, fans are programmed to analyze who should be traded and what contract a superstar should receive in order to meet complex salary cap rules, most of which they understand. Perhaps talk of rule changes can garner attention in a crowded sports and entertainment landscape, but part of me wants some of this debate on what's wrong with curling to take a backseat for a while.

I heard someone ran a bonspiel in Switzerland in which blanking meant losing hammer the following end. This is one of a few concepts thrown around over the years to reduce zeroes on the board and generate more scoring. This nonsense needs to stop. If you want to create a different version of the sport (a la Mixed Doubles), fine, but you cannot remove blank ends without fundamentally altering the standard format of the game. The very nature of a blank end is what provides a subtle but very significant strategic attribute to curling not seen in other sports. Curling has never been a game where scoring the most matters or provides the greatest entertainment. Curling is a game of point differential. Each contest is a drama that unfolds over several ends, with every story looking very different than the last. Sure, an end in which a team puts their first rock into the rings and both adversaries decide to hit through to a blank is not entertaining. But find me a game in the past decade where two teams have done this for 3 ends, much less 8 or 10. The blank ends I've witnessed in the free guard zone era involve intricate shot decisions and execution throughout, often including a double take-out, sometimes on the final shot. At each stage of these ends, a team needs to contemplate whether to focus on offense with aggressive shot selection in an attempt to score two or more (risking a force or steal) or shift to a defensive strategy despite their opponent trying to create the opposite result. I've seen top teams in a Grand Slam call a timeout and discuss whether to peel or add another guard, and then watch their opponent do the exact opposite of what they had expected on the very next shot. If a team cannot blank, all of this disappears and we are left with a modified scoring version of skins curling, except the team without hammer has no incentive to force a single point from their opponent. Now the team without hammer will play defensive and instead of zeroes on the board we'll see a row of ones. The score might be higher, but the entertainment value will not. The very nature of curling is a battle for the hammer and if that aspect disappears, the game is no longer the same. Luckily, as I understand, most involved in this Swiss bonspiel did not find the new rule to be of interest. The next time someone complains about too many zeroes on the score sheet, ask them if they watched the game. I'm certain there were rocks in play, great shots to admire and enough tension to keep them from changing channels.

Back to our original debate on outlawing the tick shot in the final end. Rather than remain a cranky old codger, I'll keep an open mind and examine the data. Looking at major league baseball results since 1957, the home team wins a tied game starting the 9th inning 52.07% of the time. In curling, a tie score in the final end is simply not close to a "tied" likely outcome. Curling is closer to a tied ballgame in the final inning when a team is behind by one point with the hammer. The general rule of thumb is the team ahead one point without hammer is 60% likely to win (58.7% for men and 57.1% for women over the last 4 seasons). This is actually very close to baseball odds for the home team to win with one out and no runners on base at the top of the 9th inning (57.9%).

Looking at the last 4 seasons of world ranking events, men’s teams win 75.2% of the time starting with hammer in the final frame of a tied game while women’s teams win 70.5% of their contests. At the higher levels (Grand Slam and Canada Cup data specifically, excluding Tier 2 and the 2019 Champions Cup), over that time frame the results are 84.4% and 73.2% respectively.

Back to our baseball analogy; if we begin the 9th inning with the visiting team ahead 1 run, odds for victory for the home team are only 15%. This appears worse than that of a team tied without hammer. No one is suggesting that the team that's one run down should be given a free runner on first base to start an inning, so why provide an advantage to the team that's behind at this point?  One argument is that a team which starts the game tied without hammer has not lost any position on the scoreboard but is now at a greater disadvantage. That is true, but as stated before, curling is a battle for hammer. This is specifically why teams now compete to determine hammer in the first end rather than have it decided by a coin flip.  However, major league baseball results are consistent from 1957 to 2018. You can choose any 5, 10 or 30 year stretch over that span and it's roughly within one percent. Curling teams keep getting better and the hammer advantage appears to be increasing in this tied-at-the-end situation, at least for the top teams in the world.

One further consideration that cannot be measured in math (yet), is the fan aesthetic. A baseball team starting the last inning one down can lose many ways. A runner could reach first and steal second, a bunt, maybe a double play, anything is possible.  Even striking out the side against the top of the batting order can be thrilling. In curling, the broadcaster may come back from a TV commercial, both tick shots have already been made, and any further dramatic tension has been taken from the contest, like the air from a balloon. A baseball team down a run in the 9th inning may lose more often than the team starting the final end without hammer, but the potential for entertainment value is significantly higher.

Under the 5-rock free guard zone, when top teams have an option, some are now choosing to be 2 down with hammer in the final end rather than tied without. At first this appears to be an error as the odds to win have only improved slightly since the end of the 4-rock rule (about 11 to 13% for men and 14 to 16% for women). These results still appear to be worse than a 25% or 30% chance to win when tied. The real scrutiny comes for the very top teams. Looking at more recent data, in the toughest events, men’s teams have gone 73-7 (91.3%) since the start of the 2018-19 season when tied with hammer in final or extra end.  

Given recent results, it's no wonder Kevin Koe prefers to be 2 down with hammer rather than tied without at the end of a game. Grand Slam women teams in 2018-19 tied at the end with hammer reached a record of 46-5 (90.2%). However, this past season teams were 34-15 (69.4%) which is in line with the broader series of world ranking events and historical results. Always the danger of small sample sizes, we see women were 91.3% in the 2014-15 season, but this came in a mere 23 situations. Women’s teams should nearly always prefer to be tied without rather than down 2 with hammer in the final end, but for how much longer?

It's fair to say these recent numbers are a concern and something to keep a collective eye on. To be clear, I hate the idea of changing a basic rule at the end of a game. I'm at a loss finding a comparison from elsewhere in the sports world, other than perhaps regular season NHL overtime. Everyone has an opinion on the various changes this century (shoot-out, 3-on-3, 4-on-4) but most would concur that when the play-offs arrive, when it really matters, these tweaks are thrown aside, and the game is played on. Though recent results could be an indicator of an undesirable future, concerns appear to be only with the very top men’s teams over a short period. I'd not suggest we change a rule for all because of results from one small group, but the data should be tracked and as teams improve, further scrutiny given to the results. But for now, when the games matter the most, curling should just play on. 

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