Why are the seasons 2005 and 2008 unlike the others from 1908 through 2019?

Aug 11, 2019
148
Those were the only two years in which starting pitchers as a group had winning percentages of at least .500 during that time period (bb-ref only has applicable splits going back to 1908). In all the other seasons, it was the relief pitchers who had +.500 marks. The two accompanying graphs show the fall in the percent of overall games won by starters by year, including the plunge beginning in the early part of this decade, and the average winning percentage by starters over the years, which began an upsurge around the mid-60s but also began to plunge in recent years. I do not know whether the upswing in openers is accounting for any of this recent change.
https://www.dropbox.com/s/5x881mgtv4j5n4u/Starter-reliever_win_percentage_split.jpg?dl=0

added: I thought the graphs would show up without having to click on the link.