Ok, I asked this question of Cecil a few years ago, but it was never used in a SD column:
Does it really take longer to get to first base when you slide head-first as opposed to running all the way? Every time I see this happen in a game, the announcers berate the poor guy who tried to beat the throw by diving to the bag. “You get there faster by running,” they say.
What’s the real deal?
Here is an article that says it can be faster to slide into 1st in theory but you still should not do it.
But it seems to me that most head-first sliders aren’t so much sliding as leaping to reach the bag with their hand. It seems plausible to me that one could push off the ground with sufficient force to touch the bag faster with their hand than by running over it.
I changed my answer because of a demonstration video I watched in the link above. It is possible in theory for the reasons you gave but the difference is small and it has to be executed perfectly. The recommendation is still not to slide into 1st.
If the first baseman is off the bag sliding may make sense to avoid a tag, but even then head first seems treacherous, very easy to end up with a hand injury from a slight misjudgment.
The article Shagnasty linked to points out that it is theoretically possible to briefly get the tip of your finger way out in front of your center of mass if you reorient your body to a prone position, but this advantage lasts for only a tiny fraction of a second before you begin to decal due to friction with the ground. To time it perfectly takes superhuman skills and is something not generally practiced, so players are very unlikely to get it right.
The analogy made by the article is that saying it’s possible to beat someone who runs full-steam all the way to first base is like saying it’s possible to make more money in the lottery than by holding a steady 9-5 job.
The only reason to slide to avoid a tag at first is if you are returning from the attempt to get to second. From batting, it’s an automatic (“force”) out.
I assume that you can get to first slightly faster by diving. Your center of mass is travelling at Xmph while running. You can extend your leading foot maybe 3 feet in front of that, depending on timing. If you dive, your upper body and hands can extend maybe 5 feet ahead of your center of mass due to outstretched hands, assuming you maintain Xmph while diving (good question) and cannot dive faster than you run. Once you make contact with the ground and start to slide, your speed will decrease drastically. So dive.
Top fit athlete running speed is let’s say about 20mph or about 30fps. (60mph =88fps) a dive which gets you there 2 feet sooner shaves about 1/15sec off your travel time. That’s almost photofinish territory.
of course, too, a fit athlete’s center of mass is probably higher on the body than a typical person’s, meaning arm reach advantage when the body rotates horizontal is less.
I’m talking about the first baseman not being on the bag, so there’d be no force.
Why is sliding at first base different than all the other bases?
The laws of physics are pretty much the same all over the universe, ya know.
But then , based on some of the baseball geeks I’ve met, I suppose baseball truly does exist in its own world, 
To elaborate on this (but not to labor it), sometimes a throw may pull the first baseman off the bag toward the plate. The fielder can more quickly tag the runner than tag the base. This is quite a common occurrence.
Because when you run to first base on a batted ball, you are permitted to overrun the base and not get tagged out (based on following certain defined procedures). In addition, you can get called out at first on a force out, so you are always (on a batted ball) trying to beat the ball to the first baseman, not the tag. So because you can over run first, the wisdom is that it is faster to keep up your speed by running. Second and third (in non-force out situations), you have to both avoid the tag and stick to the bag. So it’s not the physics that’s different, but the process.
At the other bases you slide to avoid being tagged with the ball when it’s not a force out, or again if the fielder is not touching the base if it is a force. The runner has to be tagged with the ball unless he is forced, meaning he can’t run back to the previous base. At first base no tag is necessary if the fielder is touching the base, it will always be a force in that case because the runner can’t return to home plate. At the other bases the question then becomes about whether head first or head first slides are better. There are reasons for both.
The reason to slide at the other bases is more because it is the best way to scrub off speed and stop quickly, therefore it is the fastest method to get to the base and stop.
No. The reason to slide is to avoid the tag. Also to not overrun the base.
Moved to the Game Room.
Colibri
General Questions Moderator
No. To not overrun the base is scrubbing off speed, getting to the base as quickly as possible, and stopping at the base. Which is what I said.
At a full run, stopping with a slide is the fastest way to stop, and is therefore the fastest way to get to the bag.
It is the way that you slide that helps you avoid the tag - hook slide, head first and reach.
Ah, that kind of makes sense. Versus my hypothetical 1/15sec, it may take more time than that for the baseman to catch the ball (arm up and forward) then swing it down to tag the runner going by. Forcing him to bend too may add to the delay before he can tag you.
So, in some scenarios, if you are running full tilt at 30fps (i.e. 3 seconds plus startup time to run the base) the baseman is not going to step backward fast enough to catch you with a force if he’s say, 10 feet forward of the bag.
But most slides stop you pretty fast - and to avoid being tagged, you pretty much have to be close to the ground all the way - a slide rather than a mid-air dive. So the scenarios where you have a short enough distance to hit the ground and slide and avoid a tag, but still close enough to slide and reach the plate before the baseman can reach down and touch you - those are pretty damned close plays.
Sliding into first base is a great way to get injured. The first baseman must place his foot on the base to convince the umpire of the out, as posed to a “neighborhood play” on second, where the baseman does not have to tag if its a multiple infielder play, in order to avoid a collision at second.
The point is that when running to first, you’re allowed to overrun the bag.
You can’t do that for second or third. So the reason to do it at second or third is two-fold: to avoid a tag (or to break up a double play) and to slow your momentum so you don’t go past the bag.
You slide into home because it’s going to be a tag play.
So if you’re sliding, you’re slowing your momentum. Much better to run full blast and beat the ball to the bag.
Many runners are adept enough to slide to avoid the tag. Often the catcher is there with the ball ahead of the runner (and if he is blocking the plate he must have the ball, else the runner is called safe), but the runner does not slide directly to the plate but slides to the rear of the plate and reaches out his hand to tag the base after sliding past it and sliding past the catcher’s glove.