The number of foul balls has increased by 11.98 percent from 1998, when baseball expanded to 30 teams, according to a FiveThirtyEight analysis of Baseball-Reference.com data. There were almost 14,000 more foul balls last season than there were 20 seasons earlier. In 1998, 26.5 percent of all strikes were foul balls. That share increased to a record 27.9 percent of strikes in 2017 and 27.8 percent last season, the top rates since pitch-level data was first recorded in 1988.
Overall, there were 26,313 more pitches in baseball in 2018 (724,447) than in 1998 (698,134). That’s the equivalent of adding 88 games, or roughly a week, to the schedule.1 A record 3.9 pitches were thrown per plate appearance in the 2017 and 2018 seasons, according to Baseball-Reference.com, up from 3.73 pitches per plate appearance in 2002 and 3.58 in 1988. And about half of the growth in total pitches can be attributed to foul balls.
For the first time since pitch-level data has been recorded, there were more foul balls than balls put in play in 2017 — and that trend continued in 2018.
Source: Travis Sawchik, FiveThirtyEight