Just how hard is it to homer at AT&T?

The last time the Giants finished higher than 25^th in homers was in 2014. An easy enough explanation is that the Giants aren’t good at hitting. This is true. The last time the Giants had a wRC+ of over 100 was in 2015. Remember, wRC+ adjusts for the park, so even considering they play in an extreme pitcher’s park, they haven’t been good.

But even visiting teams struggle to hit the ball out of AT&T Park. Last year, Grant showed that AT&T Park was completely immune to the home run revolution. Since 2015, AT&T Park has seen the fewest homers by a large margin. There have been 459 home runs hit there over the past four years. The next closest is Marlins Park at 534. The average baseball stadium has seen 731 dingers. We know that it’s hard to hit a home run at AT&T Park, but just how hard is it?

You’re probably familiar with Statcast’s barrels. A barrel is any ball that’s hit at such a speed and such an angle that a player is expected to bat .500 and slug 1.500. Not all barrels are home runs and not all home runs are barrels, but over half of barrels do go over the fence. 57 percent of all barrels tracked by Statcast have gone over the fence.

I have looked at all barrels hit at every park by both home and visiting players in the Statcast era or since 2015. I split them into two categories: barreled homers and barreled non-homers. Note that the labels are by the home team, but it includes barrels hit and allowed by that team at home. I figure that’s easier than going by stadium because I don’t keep track of the corporate sponsorship deals teams have. I still refer to Chase Field as Bank One Ballpark.

I was surprised to see that AT&T Park didn’t have the most barreled non-homers. It’s fifth behind Comerica Park, Fenway, Chase Field, and Kauffman Stadium. But AT&T Park has seen the fewest barrels go over the fence. In fact, it ranks dead last in HR/Barrel percentage (barreled home runs divided by total barrels).

We’ll have to think of a new name for AT&T South because Petco Park actually grades out above average in this category. The only other parks to convert fewer than 50 percent of barrels into home runs are Comerica, Kauffman, Fenway, and—oh god damn it, the Braves moved parks and I didn’t account for it—a combination of Turner Field and Sun Trust Park.

It’s interesting if you look at the average exit velocity and launch angle of barreled non-homers. At AT&T Park, the average barreled non-homers are tracked at 103.2 MPH and 25.6 degrees. That’s the slowest average exit velocity (though league average is 103.8), but no other park sees anything higher than 24.9 degrees. League average is 24.2. It may not seem like a huge difference, but using Statcast’s field visualizer we can see what an impact that extra degree and a half makes.

Here are balls hit at 103 MPH and 25 degrees or the average barreled non-homer at AT&T Park.

73 percent of those balls have gone for home runs in the Statcast era. The yellow dot to the left of the right field 375 marker amid all those other home runs was a double hit by Justin Bour at AT&T Park.

If we lower the launch angle by a degree, let’s see what happens.

The home run percentage decreases but not significantly. Let’s see what happens when we drop it down another degree to give it the profile of the average barreled non-homer at Dodger Stadium.

The home run expectancy drops over 20 percentage points. Increasing launch angle is less efficient at AT&T Park at least in terms of converting batted balls into home run.

If we look at barreled homers, the story is the same though less extreme. The average barreled homer at AT&T Park is hit at a higher angle (27.9 degrees) than any other park.

Because players must hit the ball higher, AT&T Park sees the fewest barrels converted into home runs: 40.9 percent. A player would convert 17 percent fewer barrels into home runs at AT&T than a league average stadium.

As mentioned earlier, not all homers are barrels. Not all homers are even hit hard. The worst home run of 2018 was tracked at just 88 MPH. AT&T is also devouring solid contact homers and cheap homers.

Here’s a breakdown of all the different kinds of home runs hit at every park. Barreled and solid contact should be self-explanatory. Cheap homers are all homers that are neither barreled or solidly hit.

Surprisingly, AT&T doesn’t allow the fewest cheap homers. That dubious honor belongs to Busch Stadium. Unsurprisingly, Minute Maid Park allows the most cheap shots with the Crawford Boxes. I don’t recall ever seeing a cheap home run at AT&T Park, but apparently 4.36 percent of all home runs in the past four years have been cheapies.

AT&T also isn’t the worst at converting solid contact into home runs. It’s only third worst behind the Oakland Coliseum and Kauffman stadium. HR/Solid% is the percentage of solid contact that turns into a home run at a given park.

If you combine HR/Barrel% and HR/Solid% and subtract that value from 100, you wind up with a metric that I am calling Projectile Dysfunction. The greater a park’s projectile dysfunction, the harder it is to hit a dinger there.

There you have it. AT&T Park has a seven-point projectile dysfunction lead over any other ball park, and 20-point lead over a league average stadium. So how many homers has this cost the Giants?

Since 2015, the Giants have barreled 431 balls at home. 170 of them have been a home run. Statcast has tracked 431 solidly hit balls from them. 34 of them have been homers.

As a team, the Giants would have hit 76 more barreled home runs and 14 more solid home runs over the last four years if AT&T were a neutral home run environment. Brandon Belt alone would have hit a combined 22 more dingers at an average park. To put that another way: the Giants would have hit 30 percent more home runs at a league average stadium.

But it gets more extreme than that. If the Giants played all their home games at the Great American Ballpark, they would hit 174 more home runs over four years. Brandon Belt, would have hit 35 more home runs at the Great American Ballpark.

Assuming the Giants hit at a league average park, they would have hit 90 more home runs over the past four years. That’s around 22 per year. If they hit 22 more home runs this year, they would only be 25^th in the majors this year, so still not great but it’s better than trying to outpace the Marlins for dead last. If they hit the extra 43 home runs they would get from playing half their games at the Great American Ballpark, they’d be right in the middle of the pack.

While it’s true that the Giants aren’t a good home run hitting team, the fact that they play half of their games in the single hardest park to hit a home run isn’t doing them any favors.