It's easy to forget now, but the Cubs briefly held a lead in Game 2 of the National League Championship Seriespresented by Camping World on Sunday. Rich Hill held Chicago scoreless through the first four innings, then allowed a leadoff home run to Addison Russell to start the fifth. Justin Turner tied it up in the bottom of the fifth, where it remained until Turner came back up in the ninth and… well, you know.
During that brief span where it was 1-0 Cubs, immediately after Russell's home run, there was a somewhat controversial play that merits further investigation. Jason Heyward grounded to first baseman Cody Bellinger, but Hill wasn't able to cover first, forcing Bellinger to take it himself. Bellinger dived into the bag, head-first. So did Heyward, who was out by a fraction of a second. Would it have been different if he'd run all the way through?
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Heyward was conclusively out, and we're not aiming to prove otherwise. But he wasn't out by much, and it was a pretty big moment in the game. After Javier Baez struck out, Jonathan Lester was allowed to bat for himself with two outs and none on. Lester singled before Jonathan Jay grounded out to end the inning, then was left in to allow a Charlie Culberson double and Turner's game-tying single in the bottom of the fifth.
Now imagine if Heyward had been safe and Lester's spot had instead come up with one out and one on. Does Benjamin Zobrist pinch-hit in that spot? Does Ian Happ? If so, does a different pitcher -- Pedro Strop or C.J. Edwards, perhaps, maybe Brian Duensing -- allow the Dodgers to score in the fifth? You can see all the fantastic directions this can go in, but it's also getting ahead of ourselves. The main question here is a simple one: Should Heyward have run through the bag?
The conventional wisdom says, yes, absolutely. The Statcast™ data, as we noted when we looked into this topic a few weeks ago, might tell a different story.
Let's start with the simple data. Heyward ran home-to-first in 4.29 seconds. We've tracked Heyward going home-to-first more than 350 times this year, and 4.29 seconds is his 14th-best of the season, putting this play in his top five percent. That's in part due to his strong hustle, because he outdid himself here. Heyward's average Sprint Speed (feet per second in a player's fastest one-second window, where 27 ft/sec is the Major League average) was a good 27.6 ft/sec in 2017, while on this play it was a stellar 29.5 ft/sec. Whatever happened here, it was not about lack of effort.

Meanwhile, let's look at this from the fielding perspective to see how quickly Heyward would have needed to get there to beat Bellinger. It took 2.27 seconds for the ball to go from Heyward's bat to Bellinger's glove, at which point the first baseman was 36 feet away from the base. (Hill, whose pitching delivery takes him toward third base, was still 51 feet away, which explains why Bellinger took it himself.)
At that point, Heyward was farther away -- 59 feet -- but already at a full run, while Bellinger was starting from a standing position. It took Bellinger an even two seconds to travel the 36 feet to the base, giving the ball a bat-to-base time of 4.27 seconds, ever so slightly ahead of Heyward's home-to-first time of 4.29 seconds. While it took Bellinger two seconds to get 36 feet from the ball to the bag, it took Heyward slightly longer (2.12 seconds) to go much longer (59 feet) from the point the ball hit Bellinger's glove. As we said, he was already running, while Bellinger was not -- though Bellinger is baseball's second-fastest first baseman.

So that's what did happen. But what might have happened if Heyward kept running? Would it have been enough to make up that tiny gap?
As we discussed previously, the forces at play here are those of propulsion, friction and extension. When you dive, your feet stop propelling your forward, so you slow down. When you contact the ground, you gain friction, so you slow down. But what you lose in speed, you can gain in extension. That is, if done perfectly -- and that's the key here -- by going horizontal to push your hands out well ahead of your center of mass, it's possible to gain a slight edge, or at least not lose any speed. The problem is that it's extremely difficult to do it perfectly.
In this case, we already know that Heyward was going at or near his top speed. As we said, 4.29 seconds from home-to-first is faster than 95 percent of his other home-to-first times this year, noting, of course, that not all of those plays were max effort.
His top tracked time this year -- of any of the three years of Statcast™, actually -- was 4.15 seconds, when he grounded into a double play on July 28 in Milwaukee. Let's consider that the absolute fastest time that Heyward is capable of. Right away, we can see we're talking about a difference of about one-tenth of a second against a play where he ran through, so we already have a good idea that Heyward couldn't possibly go all that much faster. 

Still, let's compare Sunday's play to the Milwaukee play to show how it differed. Like on Sunday, Heyward was flying down the line in July, with a Sprint Speed of 29.4 ft/sec. These two plays represented two of his four fastest Sprint Speed plays of the year, making them good comparisons. Sprint Speed expresses a player's top speed in his fastest one-second window, which is useful because it tells us where that top speed came. In July, his fastest one-second window came between 32 feet and two feet away from first, meaning he was going full speed into the bag. On Sunday, it came between 40 feet and 10 feet away from first, which makes sense: He wasn't running over the last few feet.
Remember, though, the dive did gain him that extension. Put another way, Heyward's dive began 10 feet away from first, then he propelled himself forward with his left foot. It took him .36 seconds to reach first over the last 10 feet doing it that way. In July, running hard, it took him .32 seconds to complete the final 10 feet.
Faster? Sure, ever so slightly. Enough to matter? Probably not; this was already about the fastest Heyward can go. Done correctly, a dive into first can be more effective than it seems (setting aside the usual injury concerns) and Heyward did it as close to correctly as can be done. The problem for him in Game 2 is that there simply wasn't enough time, and that's more about a 67.5 mph grounder with a three percent Hit Probability than anything else.