This analysis didn’t turn up much interesting. Although I’m not a fan of the DH rule, I had some ideas that the use of the DH had probably changed from its MLB inception in 1973 to the present day. I figured that the early DHs were the ageing sluggers like Cepeda & Oliva, and that the modern game uses a more mix-and-match approach to the DH. Nope.
I looked at regular-season starting lineups from the Retrosheet Event Files. I limited the analysis to American League lineups, because I wanted to focus on teams that used the DH most/all of the time. I included AL lineups in inter-league games when the DH was used.
I looked at the lineup slot occupied by the DH to see how that changed over the years. The table below shows the slots used for each season, 1973 through 2017. Cells are colored like a heat map, with red for the maximum and blue for the minimum.
I’m surprised how variable the data is from season to season. For example, in 1992 the DH led off 209 times (9.2%), and the following season the number was down to 32 (1.4%). Undoubtedly there were a couple of DHs in ’92 that led off regularly and did not do so in ’93. Still, the variation at all batting-order slots is more variable that I had expected. Maybe there’s a bit more consistency in the last ten years or so, but I didn’t do a numerical analysis of this.
Note that the only starting-lineup slot that was not filled by a DH for the entire season was the 9 spot, which had no DH in 1975 and 1997.
Of course, it’s clear that the DH is usually slotted in the heart of the lineup, and that hasn’t changed through history. The totals for all seasons are shown in the chart below. It’s no surprise to me that cleanup is the most common DH slot.
The other thing I looked at is how often a team used a single player as DH through the season. I looked at the number of games started by the most used DH on a team. The team with the most starts by one DH is plotted for each season, as is the team with the least starts by one DH. The mean plotted is the average of the DH leader of all teams. For example, in 1973 Orlando Cepeda started 142 games at DH for Boston (the max), while Kansas City had seven players with ten or more starts at DH, of whom Hal McRae had the most (33, the min).
The 1981 and 1994 seasons were shortened by strikes, so keep that in mind when looking at the data for those seasons.
There’s not much variation over history. I expected to see a decline in the max, but I don’t see it.
The coolest tidbit from this otherwise dull analysis was noticing that the maxima during 1978 & 1979 were 162, meaning that at least two players started every regular-season game at DH. That turned out to be Rusty Staub for the 1978 Tigers, and Willie Horton for the 1979 Mariners. Because of inter-league play, this record will likely never be broken!