Major League Baseball foul ball rates in the National League between 1988 and 1996 were surprising in many regards. While the National League yearly totals remained fairly level during this time, foul ball rates did jump during the 1994 and 1995 MLB strike shortened seasons, just as they did in the American League.
The Strike Years
Unlike the American League, the NL didn’t break the 45 foul balls per game average until the strike years. Prior to this time, the league remained at a tepid 44.3 foul balls per year. That average jumped 1.4 fouls in the 114 game season and dropped only marginally during the 144 game season.
This jump in average, as also seen in the American League foul ball averages, indicates that shortened seasons will increase the foul ball rates by about 1.5 foul balls per game on average when all of MLB is combined. To put this into perspective: This means in a shortened season (let’s say 130 games or the average for the two strike seasons), we would see nearly 200 more foul balls per team. Simple math indicates that spread over the 30 teams, we are looking at roughly 6000 more foul balls per shortened season.
Designated Hitter vs. Pitcher as Batter
While the numbers are statistically similar and only a difference of .73 foul balls separates the National League average from the American League average for this time frame, what is of special note is that this seemingly insignificant difference is most likely a result of the difference between the DH in the AL and requiring pitchers to be batters in the NL.
The seemingly meager difference accounts for roughly 1500 fouls, or upwards of that many strikes. That could equate to as many as 500 outs. Working under this theory, we are looking at the probability that the DH system actually leads to more strikes and more outs than requiring the pitcher to bat.
This makes sense in many ways. The DH is typically intended to protect the batter in front of him, so he’s more likely to swing at anything close in order to attempt to advance the runner. The pitcher is nearly always the 8th or 9th batter, rather than 3rd, 4th or 5th. The DH will swing and connect at pitches just out of reach and have developed their skills to the extent that they can better see what an incoming pitch is–fastball, curve, etc. A pitcher on the other hand, tends to simply swing and hope for the best.
Note: All data is from retrosheet.org sources. Due to a lack of complete historical data some team data are incomplete, so foul ball rates will be marginally inaccurate. Based on missing data, I estimate a +/-2 foul ball range if all statistics were available.