The graph shoes interquartile range, so this wouldn't be a factor, but worth noting: baseball also changed its rules on extra inning games in the past few years which speeds things up. A runner starts on second base which reduces the 0-run extra innings that are responsible for the 19 inning game I remember as a kid. [0]

[0] https://www.latimes.com/archives/la-xpm-2006-jul-10-sp-alrdp...