Does Age Matter? Visualization and Analysis of Shogi Games and Players

3 min readMay 24, 2019

This article is also available in Japanese.

TL;DR: Age matters and youth is powerful, but strong players stay strong for a long time.

Shogi is a Japanese variant of chess which has been played professionally for centuries. Its most interesting characteristic is the ability to capture an opponent’s piece and then use it as one’s own by dropping it anywhere on the board. This vastly increases the strategic possibilities and game complexity — it was only in 2017 that computer shogi programs were shown to be decisively stronger than the best humans. (Interesting fact: the US occupation in Japan tried to ban shogi because they saw capturing and using your opponent’s pieces as encouraging forced labor!)

I did some webscraping and analysis of a database of over 120,000 professional shogi matches dating from 1953 to the present, focusing on changes in player strength through time.

How does age affect strength?

Player winrates decreased as they got older, showing that even a lifetime of study may be unable to counter younger players with their fresh strategies and brains. This pattern is also apparent in the Elo rating (a measure of strength) by age: though there is a wide variability, the average rating clearly
decreases as age increases. On average, a player has 5.5 fewer Elo points and loses 0.4% more matches for each year of age. Each orange dot in the graphs below corresponds to a player’s strength at a given point in time.

At what age do players peak in strength? The median peak is around 31, but there are some who don’t peak until their 40s or later. Who peaked at the latest age? Genichi Ohno (大野源一, b.1913) peaked at 58 and Tsutomu Matsushita (松下力, b. 1911) peaked at 57. How could someone peak so late? One explanation is that the chaos of World War 2 might have disrupted the usual prime playing years of their 30s. Redoing the analysis only for those born after 1945, only a few players peaked in their 40s and not a single one did in their 50s or later.

Player careers, animated

In the animation below, each bubble corresponds to a player. The size of the bubble corresponds to the player’s winrate for that year. If a bubble isn’t blue, that means that the player held a title (won a tournament) that year. The names in the legend are names of tournament titles. The distinctive diagonal tilt of the mass of bubbles shows how older players tend to be weaker. As players retire or go below professional strength, their bubbles “pop” and disappear.

Let's look at the animation again, with labels for a few famous players so we can follow them. We can see Yoshiharu Habu's unquestioned dominance over the field for most of his career. Strong players reach the top of the pack quickly and stay there for most if not all of their careers.