To this day, I do not know if groundball/flyball impacts the number of home runs a pitcher surrenders, ostensibly then impacting his ERA.

It affects the GB/FB ratio. Have you even seen a grounder leave the park?

If it takes a weird bounce in the corner, yes. :p
if you're bored go to league records and check out GB\FB ratio. The worst will be guys with GB under 20.

But I find very little to support that. Sure, there are examples. But, I've never seen anything concrete or noticed a variance myself.

The correlation is more for ground balls versus fly balls, as opposed to a direct correlation to home runs. But, as Mike said, ground balls typically don't fly over the wall. Two many other variables factor into home runs (pitcher's splits and pitches, hitter's power, park factors, etc.).

If you build your pitching staff to have primarily ground ball pitchers, you want to have a strong defensive infield with good range up the middle to take advantage of that.

If you have a fly ball staff, then a strong infield defense is less of an asset. You'll want outfielders with good range. And homefully play in a home park that suppresses home runs.

Since you didn't like my first answer, here's another.

I've found that good pitchers with low GB/FB ratings tend to have a WHIP I'd expect but with a higher ERA than expected when compared to their WHIP. The difference is HRA. A guy who has an OAV of .200 is really good unless all those hits are HR.

Posted by MikeT23 on 2/28/2017 4:26:00 PM (view original):
Since you didn't like my first answer, here's another.

I've found that good pitchers with low GB/FB ratings tend to have a WHIP I'd expect but with a higher ERA than expected when compared to their WHIP. The difference is HRA. A guy who has an OAV of .200 is really good unless all those hits are HR.

It's not that I didn't like your answer. I'm just saying, same as when I look at PC just with the eyeball test, I find little evidence of a strong correlation.