LOOGY, referring to the lefty one-out guy, a term coined by Rob Neyer when they became quite popular in the early 1990s.

Here’s a chart looking at single-batter lefty-reliever appearances over the years.

Here, one-batter lefty appearances are plotted as a percentage of all left-handed relief appearances, as well as all relief appearances.

Here are a few thoughts:

• The percentage of one-batter lefty appearances has increased continually over the last 100 years, save for  marked slowdown starting in 1968.
• Although it may seem like the percentage is way down in 2013, the use of LOOGYs picks up late in the season. I imagine when rosters grow on September 1st, it must make managers more willing to throw a reliever in for a single batter. In 2012, there were 192 LOOGY appearances from September 1st onward out of 697 total for the year. That’s about 28% of all LOOGY appearances coming in the last sixth of the season. So, we can expect the 2013 season number to fall back in line with the roughly 16% figure from recent years.
• It’s interesting to note that LOOGY use jumped up in 1992, not 1993, when we might have expected. I can’t come up with any reason why the figure would jump so suddenly in one year, especially since the LOOGY use is a managerial decision. It seems surprising that usage jumped so much in just one year, but it must be down to 1 or 2 specific managers who started using one or two LHPs that way.
• It’s a bit surprising, then, that since that jump in 1992, it hasn’t changed much since. It hasn’t for example, pervaded the entire league, at least not at the same rate as it was done by the first team or two.