, 48 tweets, 18 min read Read on Twitter
Right, rugby (and other contact sport) friends, gather round and let me try to share with you some slides & ideas I presented at the @NFLResearch Conference on Collision sport in London last week. This set was on nudging safer behavior, it’s a thread. But it’ll have pictures…1/
2/ First, a philosophical issue that *SHOULD* influence actions (subtly). Change is hard. It’s resisted. That’s as true in the #NFL as it is in #rugby, and in any other sport. These quotes are basically interchangeable - players, coaches, media etc - push back against change.
3/ However, we also can’t allow the tail to wag the dog - if risk is too high, change IS necessary. But how much? The key question, for me, is how you achieve “change without change?”, as this slide asks? Change X but not Y (the sport) (too much). That’s key to getting buy-in.
The process of trying to navigate this balance starts by understanding how the injury occurs? What is the mechanism? Where are the most likely preventable injuries? From 2015-2017, we (@worldrugby, in partnership with @mattjcrossie who was with the RFU), studied 611 head injuries
@WorldRugby @mattjcrossie 5/ The study found, among other things, that tackles are the most numerous AND highest risk (these are different things) injury event. Not surprising. What *IS* surprising (slightly) & crucial, is that the TACKLER has head injury risk 2.6x larger than the ball carrier (see right)
6/ This is really important, because you should by now be asking “If the tackler is most at risk, then what change do you make to protect a player who instigates an action that he himself causes?. It’s easy(-ier) to protect the recipient, the ball carrier, not so easy the ‘doer'
7/ Your 1st thought might be 1) Tackler technique, & 2) Law change. Yep, ours too. But 1st, we still needed to understand EXACTLY what tacklers do that increases their risk. So we studied 464 Head injury tackles and 4000 tackles not causing injury to develop a ‘risk spectrum"
8/ This is really important because once we have this risk spectrum, we can consider options, like banning the most dangerous actions, or trying to substitute high risk for low risk (both law related), or changing high risk to lower risk through technique intervention, as shown:
9/ I can’t stress enough that this propensity method is THE ONLY way to manage risk - if you don’t know injury risk per 1000 EVENTS, then when substituting one behavior for another, you cannot account for “exposure”. So doing it by time, number or % is flawed & may make it worse
10/ So we looked at about 16 characteristics of the tackle. Here is the high level summary, somewhat oversimplified, of the key “isolated” tackle characteristics that have high risk and low risk. Some are obvious (speed, direction), some less so. #rugby #injury #concussion
11/ Next step - science MUST step aside. Our job is to describe risk, control for confounders. Once a risk picture is known, rugby experts must advise on how to change, not docs & scientists. So we gathered a group of 15 for intensive discussions, asking “How do we shift left?"
12/ Those experts - coaches, players, referees, former players - said “No way do you shift the top 2. Too integral to performance & the sport”.

They said “Maybe the bottom 2, let’s think laterally”.

And they said “Focus on height & body position - it’s the teachable aspect”
13/ Sooo…now we have a mandate - get height down, and body position of tacklers bent, not upright. This is key, so let’s explore why it was identified. Heres’ the risk spectrum for TYPE OF HEAD CONTACT that injures the TACKLER. Look at the risk of head to head vs head to hip
14/ See that head to head contact injures the tackler once every 88 times (11.3/1000)? It’s 6.6 times more likely to cause head injury than head-to-hip contacts, and 22.6 times more likely than head to upper body. Key point: For safety, get heads out of one another’s “airspace”!
15/ In fact, when we group all head injuries as “high contacts” (legal, but above the sternum), & “low contacts” (below sternum), we see that the risk of head injury is 4.3 times higher when the tackler’s head is “higher”. Also, an upright tackler is 1.5 times more likely injured
16/ There’s another fascinating bit, where there’s a kind of “game theory” involved, where it DOES NOT MATTER what the ball carrier’s body position is, the highest risk is always when the tackler is upright. So irrespective of what BC is doing, we want to get the tackler bent
17/ So this is the status - how to get tackler lower? Again, this is not my job as a scientist, it’s the job of an expert - coach, player, referee. But the intent is clear - less of what you see on top (both heads in danger), more of what you see at the bottom (less risk to BOTH)
Here are gifs of those same tackles (I know they’re not identical in context, but the principle matters). First, a tackler who is upright, heads share airspace, alignment poor, both heads in danger (especially tackler’s) and the result is an HIA. This is the high RISK situation
19/ Here is the desired alternative - it’s not a huge change, but the tackler’s head is lower, his alignment is better, & as a result, his head is in less danger (remember that risk spectrum?) and the tackler’s head is almost totally out of danger (aside from whiplash or ground)
20/ So again, we ask the experts “How do we get the tackler lower?”. And we discuss this for hours, lively debate. Some people think it was done flippantly, I can assure you it wasn’t. Every option was considered. Broadly we come up with three phases (hypotheses), as shown here:
21/ Phase 1 is to more strictly apply existing laws. That would tell players “Go lower, or be sanctioned harshly”. It’s a stick approach. But making the stick bigger & using it more often. The principle is to drive a desired behavior - lower tackling - by punishing the undesired
22/ Unfortunately, a lot of people in the media and even in rugby didn’t quite get that this approach would protect BOTH the tackler and ball carrier. They thought it was only the ball carrier (because that’s how law is written). This ended up ‘undermining’ the principle a bit
23/ But this is what it looked like - apply laws more often - more penalties, more yellow cards, different behaviors, lower tackle risk. This all hinged on referees actually applying the sanctions proposed. It’s like taking the medicine - it may taste bad, but it’s good for you
24/ Your next question - did they do it? It was mine too! My next job was to track the high tackle pens & cards over the 2 seasons since the directive & law re-inforcement. Ideally, we’d assess ref behavior in totality - what they give, what they miss. For now, just what’s given
25/ So, what we find: In year 1, globally, there’s a 64% increase in high tackle penalty rate, and a 41% increase in yellow cards for high tackles. As expected. So far so good. Problem is, the yellow cards didn’t increase everywhere. In one country, it went DOWN. High variance
26/ The biggest issue though, is that this “stick” (or medicine - pick your metaphor!) wasn’t being applied often enough, nor was it strong enough. Even AFTER the change, a penalty every match, and yellow every 9 matches doesn’t look like enough to drive behavior.
27/ Next step - LATEST season data suggests continued increase in sanction, but crucial fine print - we see penalties continue to increase by 76% (good), and yellow cards for high tackles went up 13% in 2017/18 vs 2016/17. Result: yellow is given every 11.6 high tackle penalties
28/ That penalty to card ratio is a really crucial metric, because it tells you how referees perceive *severity*. In other words, they have seen and punished the high tackle, now must decide whether to card it. The 11.6 is actually higher than BEFORE the high tackle directive
29/ So, what this means is that referees are seeing and penalizing high tackles more often, but giving yellow cards RELATIVELY less often. It suggests compromise, which is to an extent human nature. The media backlash & undermining by perception in some places didn’t help this
30/ So, our next step was consultation. We consulted again with the expert group, we spoke to referees and other coaches, and we got referee input (as crucial stakeholders - they’re the people who have to “pull the lever” we identified previously, after all…!
31/ The message we got then is that on field sanctioning and carding is asking a great deal of a ref given the speed of the game and the impact of those cards on matches. As a result, we went BACK to that expert group’s suggestions, and looked at Phase 2 - the High Tackle Warning
32/ The High Tackle Warning is a modified sanction - instead of being ON field, and punishing illegal behavior, it moves sanction OFF field, punishes high RISK behavior, and does so with a large educational component. It would be used more often, but with less severe impact
33/ Let me explain how it works - remember that we identified 2 key risk factors?
1) Head to head/shoulder contact for tacklers;
2) Upright tacklers

Those are the 2 risk behaviors the HTW aims to sanction post-match. So there are only 2 questions to be asked, as shown below
34/ Let’s look at these 3 cases, one by one. In the first, the tackler is clearly upright. There is head contact, but it’s initiated by the BC ducking. So, there is NO HTW because there’s no clear head to head or head to shoulder contact. BC-iniated contact when ducking is key
35/ Next one. You’ve already seen it. The tackler is upright, there IS clear head contact, so it’s an easy call - HTW IS ISSUED. A key point - this tackler CAN choose to go high, and he’s fine as long as there’s no head contact. It puts onus on tackers to take responsibility
36/ And finally, two tacklers here. The first guy is fine - he’s bent, no HTW. The second is upright, there IS head to head contact, so he too would be ISSUED WITH AN HTW. The message is this: If you are high & upright, and strike a high, there’s a post-match sanction.
37/ So, let me stress, at present there is NO HTW in the sport. This is a concept we are exploring and studying right now. It was however used at the U20 World Champs this year, and it was a 2 person, 3 step process, summarized in this slide at the bottom:
38/ At the U20 World Champs, this was used. Did it work? I’d love to say a loud “YES”, and in truth, I’m encouraged by the result - we had fewer concussions than in any tournament since the HIA was first used. This graph shows rate (y-axis) and number (in 30 matches).
39/ However, much as I’d like to “claim it”, it would be scientifically dishonest to do so - the tournament is only 30 matches, there are so few concussions normally, that this may be normal variation. It’s encouraging, but it’s not proof. We need more data before we truly know
40/ What is interesting, and our *thinking* at this time, is that the educational aspect around the HTW matters more than the actual HTW. Before the tournament, this concept was explained to every player, coach & referee. The message is delivered THROUGH the HTW & repeated often
41/ In the U20 tournament, in 30 matches, 11 HTWs were given. Every one comes with the re-inforcement of the “upright, high contact is bad” message, and that is the most crucial thing, I think. I think (and this is my opinion) that the crucial barrier here is communication.
42/ The premise of the HTW, by the way, was that if a player got 3 HTWs, they’d serve a one-match ban. But the true value might be that in giving them to player A, players B through Z hear the same message, over & over, constantly reinforced. We are exploring how best to do this
43/ And finally, Phase 3 is a lowering of the height of legal tackles from the current shoulder line to the armpit/nipple. This was done in the U20 trophy, and the RFU are doing it in their Cup competition. It’s too early to even say what this is showing, so I won’t speculate
44/ What I WILL say is the main outcome of these height trials (for me, anyway), is logistical. Can referees enforce the change? Does it create massive inconsistency (already a challenge)? We discussed this option with our experts & there’s a reason it was suggested as Phase 3!
45/ When you lower legal height, then any situation of a BC ducking (like the one I showed earlier, and this one) creates a dilemma for the ref, because they’re all “high”, but they’re ball carrier initiated high contacts. This might be “too much change”, going back to tweet 2!
46/ So that’s it. My talk, in tweets! Sorry for the length. The key point is this: How do you change without change? Sometimes, what looks good in theory fails because the people who must implement can’t go as far as they need to. We are navigating this issue all the time.
47/ Sometimes we fail. We go too far, or not far enough. We fail to communicate the process & intent. I get that. We deal with humans. But what I hope you can tell is that we’re trying to change it without changing *it* (the ‘DNA’), and we’re doing it systematically
48/ Again, sorry for length. I’m going to take the thread and turn it into a blog post too, so people can read it that way, but thanks for following, & please do share the thread, because I think the more the message gets out the better for safety. Cheers!
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