Win Expectancy or Win Probability is a way to use historical values for goal scoring, the time remaining in the match, home field advantage, cards and penalties to look at how a team should do in various game states. Graham MacAree over at We Ain't Got No History developed this a few years ago developed this a few years ago. Back in 2010 and early 2011 I applied the spreadsheet to MLS play.
Then we both stopped. Goals change games. With most leagues having about 2.5 goals a match the team that scores first pretty much wins. Thinking back on the way Seattle Sounders FC have played this year, and the higher goal scoring in MLS (nearly 3 goals a game), the charts should have more curves to it. They would be a bit more interesting. So, in an effort to give you more content, which is the old content that I used to do, let's see if these charts have some meaning.
That's that classic 4-4 draw down at Providence Park. That's exciting. Just see all the momentum shift back and forth.
The win over Colorado doesn't have as much movement. Leads weren't exchanged, instead Seattle dominated and the curve looked like a simple, easy three points quite early in the game.
That's dominance, early and true.
It's a fun tool at times. It can tell us some things, but with so few discreet events, it can't tell us much right now. I could input corners and that would make things a bit more jagged, but it takes about 40 corners to equal a goal. Every other event has a value assigned to it that relates to whether a team executing that event at that period of time is more likely to win or lose due to the event.
To be clear, I'm not the expert when it comes to math and analytics. I like to surround myself with those wiser and smarter than I am. I then try to apply the things they develop to expand my knowledge base. Hopefully, I can try to translate from the expert to the general public. In Children of Dune Herbert says,
Above all else, the mentat must be a generalist, not a specialist. It is wise to have decisions of great moment monitored by generalists. Experts and specialists lead you quickly into chaos. They are a source of useless nit picking, the ferocious quibble over a comma. The mentat-generalist, on the other hand, should bring to decision-making a healthy common sense. He must not cut himself off from the broad sweep of what is happening in his universe. He must remain capable of saying: "There's no real mystery about this at the moment. This is what we want now. It may prove wrong later, but we'll correct that when we come to it." The mentat-generalist must understand that anything which we can identify as our universe is merely part of larger phenomena.
- The Mentat Handbook
That's what this is an attempt at doing. It applies things that to the expert make sense, but are not good enough. But for the fan, or the not quite expert, maybe we can learn a bit.
From this match we learn that it wasn't the penalty, or the goal from it that made the win most likely for the Sounders, but Martins' first goal. That's when things shifted from pretty likely Seattle win with a chance for Colorado to a damn likely Sounders win with a chance at a draw.
Goals change games.
That's basically what all the fancy math winds up saying. The coaching truism is backed up by math. In this case, the second goal shifted every thing. On the road, where teams have nearly a half-goal advantage one goal is not enough. Two almost certainly is.
Goals change games, and in this game Obafemi Martins changed it - a lot.