In professional bowling,

about 60% of the shots are strikes.

But what about the rest of the shots?

There are a little over 1,000 possible spare configurations,

and players convert the hardest less than 1% of the time.

So, what's the most difficult spare of all?

Well, there are a lot of notorious spares out there.

But today, we're gonna be looking at

the most notorious of all: the 7-10 split.

Now, look, some of you may have noticed

that this episode breaks with our format a little bit,

because unlike previous feats that we've looked at,

people have actually hit 7-10 splits.

[Commentator] Oh, look at that!

Here's the thing, nobody on Earth

can hit a 7-10 split predictably or reliably,

and that's because that split is even harder than it looks.

So today, we're gonna look at why converting the 7-10 split

is really, truly almost impossible.

To find out what it takes,

I played a few frames with a professional bowler--

I believe the 7-10 is the hardest spare split conversion

to make in bowling.

[Robbie] Tried hacking the game with a bowling robot,

and crawled inside the jaws of a pin-setting machine

to find out what really makes the 7-10 split

the most difficult spare of all.

This has been turned completely off,

which I am grateful for.

But first, I went bowling.

I've made the 7-10 three times in my lifetime,

and I'm 43 years old.

I've been on tour for going on 19 years.

That is 10-time national title-holder Wes Malott.

We met up with him at the US Bowling Congress

in Arlington, Texas.

Do you have any pro tips on how to convert this thing?

Well, I'll tell you one thing.

In order to make two, you gotta hit one.

[Robbie] In other words, accuracy is essential.

Come on!

It's also not my strong suit.

Come on!

It's hard to hit the one!

At least, for me it is.

Malott can hit whatever pin he wants almost every time.

But there's more to converting this spare than accuracy.

And to fully appreciate why,

it helps to understand the anatomy of a bowling lane.

It's 42 inches wide and 60 feet

from the foul line to the head pin.

That's pin number one.

The nine remaining pins are numbered like this.

Each pin stands 12 inches away from its neighbors,

creating a pattern of equilateral triangles.

Two gutters run alongside the lane

and trap the ball if it strays too far left or right,

removing it from play.

Bowling just boils down to angles.

When the ball and pin collide,

the pin bounces in a direction

perpendicular to the tangent plane

that intersects with the point of contact.

So, if you hit the pin here, it'll bounce here.

Hit it here, it'll fly here.

And if you hit it here, it'll go this way.

That means that in order to send the seven pin

flying across the lane and into the 10 pin or vice-versa,

in theory, you need to hit it right here.

Here's the problem:

It is impossible to get a bowling ball

far enough outside the seven or the 10 pin

without it first falling into the gutter.

There's just not enough room.

That makes the 7-10 split the only spare in bowling

that can't be converted with ball and pins alone.

To pull it off, you actually have to bounce the seven pin

or the 10 pin off the machinery behind the pin.

And the more power on the shot, the better.

When Malott goes for the 7-10 split,

he throws at about 22 miles per hour.

That's harder than he usually throws.

And he often gives it a little bit of forward spin

so the ball won't hook and lose speed.

But there's one more essential ingredient

for converting the 7-10 split: luck.

Even if you hit the pin hard enough

and even if it heads toward the pinsetter at a good angle,

there's just no telling how it's going to ricochet.

Without some kind of lucky bounce

in the machinery in the back end,

you're just not gonna convert it.

And that's because this isn't like banking a shot in pool.

For starters, the pins have a funny shape

that causes them to bounce around unpredictably.

But you also have to consider the barrier behind the pins.

It's a curtain, not a wall, which means that it moves,

and anything bouncing off of it

is gonna ricochet around even less predictably.

And some of those curtains move more than others.

Here's what I mean by that.

Okay, so unless you work at a bowling alley,

you've probably never been back behind here.

This is a pinsetter.

It's what collects and sort of repositions all of the pins

every time you're bowling.

And the piece that we wanna look at is in here.

Okay, so this is an older model pinsetter.

It's anchored in two places: once up here at the top

and again down here along this more solid bumper section.

When you're trying to convert the 7-10 split,

the goal is to bounce either the seven pin or the 10 pin

off of these surfaces and into the opposing pin.

Now, what you might've noticed when I touched it

is that this curtain has some give to it,

and that movement actually reduces

the energy of the pin bouncing off of it,

which makes it tougher to ricochet into the other pin.

Here's the thing.

On newer-model pinsetters, this curtain moves even more.

And when we were at the US Bowling Congress,

we actually got to see

what one of those pinsetting curtains looks like.

On these newer mechanisms,

this curtain is only attached at the top,

and so it swings completely freely like a doggie door,

and then the pin, instead of bouncing,

all of that energy just gets absorbed into the curtain.

All of which means that in the end,

when it comes to the 7-10 split,

your best bet is to hit either pin

as hard and as consistently as possible

and then just hope for the best.

And when it comes to consistency,

no bowler on Earth is as reliable as this one.

Meet Earl.

That was mildly terrifying.

Earl is our staff bowler

here in the Equipment Specs Department.

He's a robotic arm and he throws bowling balls

very, very, very well.

[Robbie] Earl can put a bowling ball

pretty much anywhere you want at up to 24 miles per hour

and at spin rates as high as 900 rotations per minute.

That's triple what pros put on their shots.

And once you've dialed in all your parameters,

Earl can roll the same shot over

and over

and over.

Normally, the US Bowling Congress

uses Earl to test equipment,

but today we're gonna use it for an experiment.

The goal: to see if Earl can hit a 7-10 split.

Come on, Earl.

I'm changing the trajectory from 1.7 to 1.2.

To increase our chances of hitting the spare,

we decided to let Earl bowl on a lane

with an older-model pinsetter with a fixed curtain.

We tried bouncing it to the side,

at an angle towards the middle of the curtain,

and even got the pin to double-bounce off the ball.

And while some of our shots

looked like they might have come close

to converting the spare,

we never managed to actually pick it up.

Earl might be powerful and consistent,

but not even a robot can engineer luck.

So, if you bring all of these factors into consideration,

you wind up with a conversion rate

on the 7-10 split of just 0.7%.

But there is a spare that players hit even less often.

Everyone talks about the 7-10 split.

Is that actually the hardest shot?

This is data journalist Ben Blatt.

A few years ago, he analyzed close to half-a-million frames

from the Professional Bowling Association

to try and figure out

what the hardest shot in bowling really is.

So, you analyzed close to half-a-million frames.

What did you find?

Their conversion that was picked up least often

is a shot that actually has a nickname

called the Greek Church.

It was picked up about 0.3% of the time

compared to the 7-10 split, which is about 0.7% of the time.

So, they're obviously both extremely hard to pick up,

but the Greek Church statistically was converted

much less than the 7-10 split.

[Robbie] If you've never heard of the Greek Church,

here's what it looks like.

For right-handers, it's when you leave

the four, six, seven, nine, and 10 pins.

And it's the mirror image

of that pin arrangement for lefties.

It's called the Greek Church

because if you look at the pins head-on

and use your imagination,

they look a little bit like the spires of an old cathedral.

To convert it, you need to hit all the pins on one side

while sending at least one of them across the lane

to knock over the remaining pins.

It's a highly technical and very risky shot.

If you miss, which you probably will,

you earn far fewer points

than if you go for the three pins you know you can hit.

That second strategy is called going for count,

and bowlers typically do it

when the encounter difficult spares.

If you're in a game-time scenario,

strategy more often than not

calls for just picking up the three on the right.

Most of the time, yes, you're going for count

and you're going for the three on the right.

[Robbie] But let's say you're going for all five pins.

Is the Greek Church actually harder than the 7-10?

Not according to Malott.

I think the 7-10's harder than the Greek Church

because the Greek Church, you can shoot at it

and you've got a pin that can slide across

to make the other pins.

A 7-10, they're even farther apart

and it's virtually impossible

because the lane is only so wide,

you can't hit that side of the pin

and get it to slide over to the seven pin.

[Robbie] To prove his point,

Malott agreed to try converting the Greek Church.

He struggled at first.

It is, after all, a really difficult shot.

But it only took him about a dozen attempts

to finally convert the whole spare,

and he came pretty close three or four times.

We saw similar results from Earl.

Once it was dialed in,

the robot was able to convert the Greek Church

about 40% of the time.

But neither our human bowler

nor our robotic one could convert the 7-10.

So, if the professionals still think the 7-10 split

is harder than the Greek Church,

why did it come up less often in Blatt's study?

Again, it boils down to strategy.

On the 7-10 split, it's the same shot

whether you're trying to knock over one pin or two.

But on the Greek Church, it's two different shots.

If you go for count, you'll probably pick up three pins.

But if you try to convert the spare,

you're going for these two pins right here,

and there's a good chance you'll walk away

with just one or maybe even none.

Even though converting the Greek Church

is technically easier,

it is almost never worth it to try in a game.

It's virtually impossible, almost impossible,

to be able to slide over

and hit both of those pins simultaneously.

Which is probably why it showed up

less in the study than the 7-10.

The point is, there is an important distinction

between the rarest shot in bowling and the most difficult,

a title that still belongs to the 7-10 split.

Because, remember, without that pinsetting machinery

behind it, you cannot convert the 7-10 split.

So, unless that machinery changes in some way

to bounce pins more reliably or predictably,

the 7-10 split will remain almost impossible.