Last night's Game 7 saw the first replay reversal in the World Series, at the tail end of Joe Panik's ridiculous double play. It was a huge play by Panik—the difference between first and third with no outs and bases empty two outs in a one-run game—made possible by replay. It was also made possible by Eric Hosmer sliding face-first into first base like a shithead.
As soon as Hosmer went to ground, baseball nerd Twitter lit up with takes. You might have seen Bill Nye pop his head in to say this:
This is correct! More or less. There's a liiiiiittle more to the debate, which is why it's managed to survive as a debate for so long, instead of receding into modern common knowledge. Alan Nathan, who's more or less the last word on physics in baseball, went to bat for sliding:
And this is also true. If executed perfectly, it's possible that you're going to reach first base faster than if you run through. Understanding exactly how that happens is important to understanding what sort of risk proposition you're co-signing.
Here's one of the times where ESPN's Sport Science manages to actually be useful. In the video below, Sport Science demonstrates that as a runner begins to lay out for a slide, he actually pulls ahead of a runner running through the bag. This is because your center of gravity continues its forward momentum while also moving it closer to the bag—vertical momentum—and for a brief pico-moment, you've gained an advantage. But like the Science Guy observed, once you leave your feet, you've lost all power to thrusters, so the lost extra step catches up almost immediately. And worse, if you drag on the ground for any length of time, you're slowing down even more rapidly.
Still, it's possible to come to the conclusion after watching the video that if you execute a perfect slide—beginning your dive far later than a traditional head-first slide, to maintain propulsion and minimize the chance you drag on the ground—it will be faster than simply running through. This is likely demonstrably true, but the key concept in the previous sentence isn't whether not the thing is possible—it's "simply."
It doesn't actually matter if sliding is theoretically faster than running through if the sliding proposition requires precise timing and mechanics that no major leaguer employs—Hosmer certainly didn't. And even if players began to optimize the first base slide (ignoring injury risks), it's not like that's a repeatable process—you're going to get a lot of variance. Running through, on the other hand, is exactly repeatable.
In a setting where players haven't been trained for the physics-approved sliding method and, more crucially, don't have mental clocks calibrated finely enough to fire the dive at the exact hundredth of a second necessary, the blackboard ideal of a slide being faster than running is exactly as relevant as saying something like, "If you play the lottery, you can absolutely win more money than you'd get at a 9-to-5."
But even under that premise, the temptation is to look at this as a problem of risk tolerance—a gamble or gut instinct by a savvy veteran or a brash rookie—but this is also a wrongheaded. As a rule, humans are bad at evaluating risk, letting biases and fears inflect decisions beyond their material probabilities; but we're particularly bad at lining up cost and benefit when one side is orders of magnitude less valuable than the other—especially when there isn't a cheat sheet (a two-point conversion card, or the book says in blackjack) to guide our decisions. There's such a wide variance on how much a poor slide can slow you down, and such a seemingly narrow window through which to thread a productive one, that it's hard to imagine an argument to go for it. Problem is, going for it still feels like going for it, when really, it's just getting taken.