One of the more overlooked thrills of watching a live baseball game occurs the precise moment when you recognize a baserunner has decided to challenge a fielder by taking the extra base. There is so much suspense and drama packed into that tiny instant when the casual trot of the runner rounding first suddenly transforms into furious sprint, and the crowd’s anticipation of the fielder’s throw suddenly becomes deafening.

A few months ago, however, I discovered that the frequency of this wonderful spectacle has sadly been in steady decline over the years. By measuring the receding number of plays at the plate since 1950, it seems there is evidence that baserunners as a whole are evolving rather quickly into cautious pragmatists utterly adverse to any form of excitement, rather than the wild and reckless glory-hogs we found so entertaining.

This morning I wanted to examine baserunner moxie when the stakes aren’t quite so high as being thrown out at the plate. In other words, have baserunner habits changed when it comes to simply advancing from first base to third on a single?

Sure, it’s not as romantic or emotionally-thrilling as rounding third in a fury and plowing through the catcher, but swiping third base from a slow-footed or unsuspecting outfielder can have equally important implications later in the inning.

If we isolate all those situations in 2012 where there was a lone baserunner on first base while a single was recorded, we can get get a quick glimpse of baserunners’ behavior patterns by looking at the resulting base state immediately after the play. (This excludes bunts and plays in which an error occurred.)

Start Base State End Base State Outcome% “1–” Bases Empty 0.04% “1–” “1–” 0.93% “1–” “-2-” 0.27% “1–” “12-” 70.37% “1–” “–3” 0.56% “1–” “1-3” 27.10% “1–” “-23” 0.72%

Just over 70 percent of the time this past season, the runner on first decided to leave well enough alone and hold tight at second base. Meanwhile, roughly 28 percent of the time did the baserunner seize the opportunity to advance to third on the play (including the rare occasions where the hitter then followed him to second base). Interestingly, an out of any kind was recorded in less than two percent of these situations.

For the most part, this jells with my impressions of present day baserunning habits. A 70/30 split on holding vs. advancing makes complete sense, though I will admit to being slightly surprised by the low out total under this scenario. Perhaps the image of a baserunner being thrown out trying to hijack third base from the defense has a way of standing out in our memories, making it seem as though the event occurs more often.

So while these data may certainly agree with our impressions of the most recent baseball season, what about historically, then? Have baserunners always been this cautious?

If we similarly add up all the occasions where the resulting base state was either “1-3” or “-23” and define this as successful “first-to third” percent for all seasons back until 1950, then Retrosheet clearly says the answer is “no.” (I am also ignoring the rare “–3” outcome states where the lead baserunner was likely to have advanced during a rundown of the trailing runner.)

Baserunning in the 1960s was far more aggressive than it had ever been in the Retrosheet era, with Golden Agers grabbing the extra base a remarkable 35 percent of the time. These habits then rapidly curtailed in the ’70s, before experiencing severe decline as baseball entered the 1990s.

There is certainly a noticeable relationship between more brazen attitudes on the basepaths and run environment, as we’d probably expect. If the sluggers batting behind you are more likely to drive you in from second base, it makes sense not to risk getting thrown out at third needlessly. For this reason, we see that this form of aggressive baserunnning peaks appropriately in the run-deprived “year of the pitcher” 1968 season and subsequently falls into a deep slumber during the homer-happy era at the turn of the the century. In fact, overall from 1950-2011 there was a correlation of r = .43 between seasonal first-to-third percent and runs per game.

So it makes sense that with the recent onset of what is quickly proving to be a new brand of “pitcher’s era,” baserunners are once again opting to take more chances. This is evidenced by the sudden jump in first-to-third rates beginning with the 2010 season.

But while contemporary baserunners might have more motivation to take the extra base than their recent predecessors, this does not mean that they will be more prone to making more outs in first-to-third situations. In fact, we might even expect them to make even fewer outs on the basepaths in the near future. This is because while the rate of successful first-to-third advancements seems to coincide with offensive fortitude through the years, the rate of making outs in these situations has declined steadily since 1950, regardless of run-environment:

This leads us to believe that baseball is becoming more responsible on the basepaths as it matures. Perhaps the inspiration behind this trend is philosophical; perhaps managers and organizations have learned to appreciate the value of an out, or in this case: the non-out. As front offices learn to appreciate the benefits of on-base percentage and low caught-stealing percentages, so too have they learned not to surrender outs on the basepaths.

But we have to consider that along with changes in the way the game is viewed tactically, there may be other factors in play. For instance:

{exp:list_maker}Ballparks are getting smaller, allowing outfielders to close in on the gaps.

Speed has been devalued in favor of power, leading to slower baserunners.

Outfielders are becoming more effective, perhaps with stronger arms. {/exp:list_maker}

Some of these reasons certainly might play a more significant role than others in evolving baserunning habits, and it’s a good bet I may have even missed a few potential explanations. I would love to hear your thoughts on all this.

References & Resources

Thanks to the fabulous Retrosheet files for their never-ending source of intrigue.