How can we assess performances in stage race pursuits?
As with most stage races these days, the Tour de Ski included some handicap start pursuits. Generally, the athletes will start in a staggered fashion based upon their time back in the overall standings, and the first person to the finish line wins the stage.
This creates some very unusual incentives for the athletes, depending on where they are in the overall standings. Many of the athletes are no longer really racing against each other, only those skiers who happen to be near them in the overall standings. For example, there’s no really sense in which Therese Johaug was racing against Liz Stephen in Thursday’s pursuit. Johaug only really cared about maintaining the gap behind her and trying to catch the leaders.
This means that isolating the times for just that stage is an almost useless way to gauge performance. Johaug, for instance, skied that stage around 15 seconds slower than Stephen, but we probably don’t think that that means much about Stephens’ ability compared to Johaug’s.
So I wonder about these things when I read stuff like this, or this, talking about how well Stephen and Freeman skied in the pursuit based on their times for just that stage. By my calculations, Freeman had the 11th fastest time of the day and Stephen the 13th. But that alone doesn’t mean much to me, since many other skiers were really only racing against the skiers near them, rather than the whole field.
If an athlete says they had a good day, of course, I’m inclined to believe them. They alone know how their body felt and whether it was a good effort. But, you know, I like to measure stuff, so let’s try.
Let’s compare Freeman and Stephen only to those skiers who started near them in the pursuit. Specifically, how did Freeman and Stephen’s times for the day compare to their historical performances against these skiers? Better than average? Worse? About the same?
Here’s the relevant graph for Freeman: Read more
Liz Stephen’s Distance Preferences
I was skimming FasterSkier’s write-up of the Tour de Ski prologue yesterday and noted their comment about how Liz Stephen “… is generally stronger over longer distances, performing better in 10k’s than 5k’s and even better still in 15k’s.”
That has been my informal impression as well, but I was suddenly skeptical about whether her actual results would bear that out as clearly as you might think. Specifically, I started wondering whether this may be a situation where how you measure results has an impact on how we perceive their quality. For instance, here are her WC level distance races, filtered down to only 5, 10, 15 and 30 km distances, measured by finishing place:
In 2009, longer distances were definitely better. Then things looked kind of mixed in 2010 (generally an off year), before returning to normal in 2011. So far this season, this look fairly mixed again, although with only a single race over 10k.
However, the longer races (15k/30k) are usually mass start or pursuit races. They can sometimes have smaller field sizes and are often paced much slower. (Although I think the difference is probably not as pronounced with the women as it is with the men.) If we look at the percent behind the median skier, which corrects for some of the differences between interval and mass start races, we get this:
Things look the same for 2009: noticeably better at the longer distances. Now, though, 2010 doesn’t look “mixed”. Rather, it seems she skied quite a bit better that year in the 10k’s (again, having a generally off year). But then both 2011 and 2012 look fairly mixed to me, with some good races at several different distances.
So I think her results have displayed a modest tendency to be stronger in longer distances, but not quite as much as you might think by looking only at her finishing place.
Rogla Distance Races
Oh yeah, there were some distance races in Rogla on Saturday too, huh?
Once again, this will be short on the words; just some pretty pictures. The US women had another strong outing:
Once again I’d note the continued downward trends for Holly and Kikkan and the generally flat trend for Liz. (Ida still has too few races for trends to be particularly meaningful.) In particular, I would emphasize that Kikkan’s classic skiing is showing the sort of trend her freestyle skiing has shown for a few years now:
Alex Harvey and Devon Kershaw were probably hoping for more on Saturday, and although their results weren’t terrible, they also weren’t all that great (for them):
The final thing I’ll note is that I noticed that the Russian women put three folks in the top ten on Saturday, a fairly strong showing for them. A sign of a resurgence for the Russian women? Well…
In Ivanova’s case, that race appears to be at her ceiling (or floor, I suppose if we associate down with better performance). As for Iksanova and Medvedeva, it’s still a bit early to tell, but it’s a good sign for those ladies to be starting out with results in the negative zone of these graphs.
Davos Recap
North Americans
Each weekend seems to be an interesting mix of results for the North Americans. Starting with the women (Davos result circled in blue):
Compared to this season, that was an off day for Kikkan, but compared to last season that was pretty typical. Part of me wonders if she dialed it back a bit late in the race when she knew she wasn’t feeling strong to save some energy for the sprint. But as you can see from her graph, if that’s going to be her “bad” race this season, she’s going have a strong set of results this year.
I’m very cautious about jumping on bandwagons when someone pops a good race or two, but Holly Brooks is beginning to convince me. That’s three good (and one OK) distance results in a row now. More importantly, I like the direction her trend is heading. It’s still early, so it’ll only take a few mediocre races to flatten that trend out, but so far it looks promising.
You can’t deny that Liz Stephen has had some strong results so far this season. My only concern is that they have all been roughly where we’ve seen her topping out before. Can her good days inch up towards the top ten?
As for the men: Read more
Hoffman & Stephen In Seefeld
Christian Hoffmann
Christopher Tassava chimed in with another request, regarding the news this week about Christian Hoffman’s 6 year suspension. Since I did post looking at who stood to gain if you removed Andrus Veerpalu from past results, he wanted to know what it would look like if we did the same thing with Christian Hoffmann.
It turns out in this case that the beneficiaries aren’t nearly as concentrated on a few individuals, so I’m going to pick and choose who I highlight here. Removing Hoffmann from the results would impact the winner in three instances. One is of course the famous 2002 Olympic race, in which the “official” second place finisher was Mikhail Botvinov, so let’s just call that new podium Skjeldal, Piller Cottrer and Bjoerndalen. For the other two, it would have meant regular WC victories for Teichmann and Sommerfeldt.
Ultimately, I think Piller Cottrer and Skjeldal would have the biggest complaints, since they also would be bumped up from 4th to 3rd on at least one other occasion. Alexei Prokourovov would also have gained two 3rd place WC finishes, but the rest were split between a range of skiers.
Moving back to the top ten, we can turn to an American, Carl Swenson, who would have notched two more top ten results. Vincent Vittoz would have picked up three additional top ten results.
As for scoring WC points at all, we can identify a few North Americans again: Carl Swenson would have picked up WC points on two more occasions, James Southam (once), Donald Farley (once), Stephan Kunz (once) and reaching way back, Marcus Nash (once). At this level, the list of names is an eclectic mix of the famous (Piller Cottrer, Elofsson, Hjelmeset, etc.) to the not so famous (Diego Ruiz, Kay Bochert, Peter Michl, etc.).
In all, 90 different skiers would have gained an additional top 30, top 10 or victory. That includes several other skiers also suspected or convicted of a doping offense. Maybe during the off-season I’ll attempt a more complete assessment that attempts to remove every single skier possibly connected to doping, but that’s a bigger project.
Seefeld
Some of the other US skiers skipped the sprint relay to do a FIS race in Austria on Sunday, and by all accounts skied fairly well. Liz Stephen rather handily won the 5k freestyle, and Noah Hoffman finished 3rd, 9 seconds ahead of Kris Freeman.
But of course, comparing Hoffman to just Freeman is risky, since any one skier can have an off day. So let’s see how that result compares to his past results against the entire field:
So, remember that positive, higher values indicate better performances for Hoffman. Up is good.
The blue dots are from this particular race in Seefeld (notice only two are below zero, corresponding to the folks who beat him). You can see that this is more or less in line with how he’s fared against these skiers in past seasons. Perhaps a little better, but not dramatically so.
As for Liz Stephen, here is the equivalent graph for her race: Read more
Sjusjøen Recap
Finally, the World Cup season is under way. The individual 10/15km freestyle races this past weekend had some predictable performances (the Norwegian women) and some not so predictable performances (Swedish men).
Men
Let’s focus on just three of the men with notable performances on Saturday:
Definitely strong races for each of these guys, but there are some differences. Note that in Johan Olsson’s case, the past three seasons have seen him more or less plateau, and maybe even fall off a bit. He hasn’t laid down an effort quite like that in some time. Given his age and the trend over the past few seasons, I’d guess that we aren’t going to see Olsson pull this rabbit out of his hat each weekend, but you never know.
Calle Halfvarsson, on the other hand, is quite young, only around 22 I believe. For some reason I had it in my head that he was more of a sprinter, but looking back at his results I see now that he’s not quite that lopsided. He has racked up a 1st and 5th place in the WJC sprints, and several top 30 appearances in WC sprints, once as high as 9th. His distance results haven’t looked quite as impressive, but they certainly haven’t been poor. One interesting point to make is that after some strong WJC results, Halfvarsson had some strong results in WC races last season, including the sprints I mentioned. But he didn’t fare well at U23′s last year, finishing 23rd, 25th and 27th. This is a good reminder that you can’t put too much emphasis on a single set of championship level races in evaluating skiers.
All that said, this Saturday’s race was clearly out of the ordinary for him. I’d guess this performance is a good sign for him, but I wouldn’t expect him to do this every weekend this year. Even if this is his best result of the season, and the rest of his races fall between this performance and his median from last year, that would represent an enormous jump.
There was plenty of excitement about Alex Harvey’s 5th place, particularly on this side of the Atlantic. In contrast with Olsson and Halfvarsson, though, this result doesn’t look nearly as extreme for Harvey. If anything, I’d call this a strong race, but not at the outer limits of what he’s shown before. That’s why I’m taking Alex Harvey very seriously this season. Read more
Beitostølen Recap: Freestyle Races
There were only a handful of Americans (and no Canadians) who did the freestyle distance race in Beitostølen, Norway on Sunday, so we’ll cover them and Andrew Musgrave in one post.
First a rough look at how each performance stacked up in terms of FIS points:
By FIS points, that’s about as fast as Arritola has skied, although that’s an imperfect measure of course. Tad Elliott is typically a much stronger skater, so it’s not surprising he had a somewhat better day as well. Musgrave’s race looks ok, but not spectacular.
Before I break these down further using percent back difference plots, I need to say a few things about some peculiarities in graphing head-to-head match-ups measured by the difference in percent back. When I make these graphs, I have to make a decision about how deep in the field to go. For instance, am I really interested in how Musgrave has fared against the folks in 200th place in a race like this?
As much as I can, I try to make a reasonable decision here, but it can vary from graph to graph. If someone finished 25th, I may only compare them to the top 40; if someone finished 60th out of 130 I might go all the way back to 80th place. I also on occasion will go a bit deeper than usual for skiers who have not raced in Europe as much, in order to catch a bit more data to work with.
Long story short, since many of the Americans were higher up the results sheet today, I didn’t have to go as far down to get some decent comparisons. This means the graphs can look quite a bit different from Tuesday’s versions.
Anyway, let’s get Andrew Musgrave out of the way first: Read more
Recent Comments