Other than stadium effects and power of hitters-faced, are there specific attributes of a pitcher that gives up home runs? I figured it would be a function of velocity and GB/FB, but anecdotally looking through data doesn't seem to be much correlation.

Low GB will lead to excess homers. The really good pitcher is worth having even if it's 0 but you'll always feel disappointed. His ERA won't match his WHIP.

Two of my best SPs - same team, almost same velocity and control ratings.

P1 - 29 GB/FB, 277 HRs in 2248 innings = 1.1 HR/9, 1.12 WHIP, 3.29 ERA.
P2 - 93 GB/FB, 155 HRs in 1522 innings = 0.9 HR/9, 1.19 WHIP, 3.33 ERA.

So yeah, it's not just the GB/FB.

Do not ever let anyone tell you that gb/fb is correlated with Hr rate or slugging percentage. I have given detailed analysis on this in ~5 separate posts in the past.

-Pitcher OAV is correlated with splits
-Pitcher slugging percentage is correlated with average pitch value (P1 + P2 etc / [# of pitches])
-Pitcher walk rate is correlated with control
-Pitcher WHIP is correlated in a basic sense by [control + splits], relative to "par values" that are not officially disclosed in the sense that fielding par values are disclosed. But they do exist, and admin has confirmed so in the most recent dev chat
-Pitcher K/9 is the only outcome of VEL attribute
-Pitcher ground ball ratio is the only outcome of GBFB attribute
-Pitcher ERA is a composite that results from all of these attributes interacting together simultaneously. vOAV + vOBP (aka WHIP), and vSLUG correlate to ERA almost exactly directly-proportionally, with high rates of K/9 and GBFB sliding ERA downwards on this scale and low rates of K/9 and GBFB sliding ERA upwards relative to WHIP. Strikeouts do not advance baserunners [this is why real-life MLB ERAs are at historical-lows as K-rates are at historical highs, and this is why ~2005-present is officially referred to as "The Strikeout Era" in the same way as 1990-2004 is referred to as "the Steroid Era" and 1900-1919 is referred to as "the Deadball Era", etc], and ground ball outs contribute to more double plays which "undo" the previous baserunner and lead to lower ERA relative to WHIP.

But do not let anyone ever tell you that GBFB itself has anything to do with HR rate because that's completely false. Take an hour or two and study league leaders and player statistics. It's plainly obvious to the naked eye let alone to actual mathematical analysis

***[In real life it does, because GBFB represents ground ball EVENTS as opposed to ground ball OUTS. In HBD GBFB is not calibrated correctly and represents the % of OUTS that are ground balls as opposed to the % of EVENTS that are ground balls. The RNG algorithm was not designed correctly.]

Sigh. It's a factor. I've tested it with single digit GB/FB ratings. Their HRA rates is higher than "normal" pitchers.

Posted by pjfoster13 on 5/19/2017 11:06:00 AM (view original):
Do not ever let anyone tell you that gb/fb is correlated with Hr rate or slugging percentage. I have given detailed analysis on this in ~5 separate posts in the past.

-Pitcher OAV is correlated with splits
-Pitcher slugging percentage is correlated with average pitch value (P1 + P2 etc / [# of pitches])
-Pitcher walk rate is correlated with control
-Pitcher WHIP is correlated in a basic sense by [control + splits], relative to "par values" that are not officially disclosed in the sense that fielding par values are disclosed. But they do exist, and admin has confirmed so in the most recent dev chat
-Pitcher K/9 is the only outcome of VEL attribute
-Pitcher ground ball ratio is the only outcome of GBFB attribute
-Pitcher ERA is a composite that results from all of these attributes interacting together simultaneously. vOAV + vOBP (aka WHIP), and vSLUG correlate to ERA almost exactly directly-proportionally, with high rates of K/9 and GBFB sliding ERA downwards on this scale and low rates of K/9 and GBFB sliding ERA upwards relative to WHIP. Strikeouts do not advance baserunners [this is why real-life MLB ERAs are at historical-lows as K-rates are at historical highs, and this is why ~2005-present is officially referred to as "The Strikeout Era" in the same way as 1990-2004 is referred to as "the Steroid Era" and 1900-1919 is referred to as "the Deadball Era", etc], and ground ball outs contribute to more double plays which "undo" the previous baserunner and lead to lower ERA relative to WHIP.

But do not let anyone ever tell you that GBFB itself has anything to do with HR rate because that's completely false. Take an hour or two and study league leaders and player statistics. It's plainly obvious to the naked eye let alone to actual mathematical analysis

***[In real life it does, because GBFB represents ground ball EVENTS as opposed to ground ball OUTS. In HBD GBFB is not calibrated correctly and represents the % of OUTS that are ground balls as opposed to the % of EVENTS that are ground balls. The RNG algorithm was not designed correctly.]

Thanks for posting -- where does catcher PC fit into the HR conversation?

Posted by MikeT23 on 5/19/2017 11:28:00 AM (view original):
Sigh. It's a factor. I've tested it with single digit GB/FB ratings. Their HRA rates is higher than "normal" pitchers.

@opie- to answer your question, catcher PC contributes to OAV. 10 points is worth .05 batting average or whatever. It's in the FAQ

@mikeT- you're not 100% wrong that low GBFB give up home runs but it's not because of HR rate itself, they give up more HR as a derivative. Your answer is sorta right but your reasoning is completely wrong.

If you control for the following:
Pitcher A (RHP) has splits of 65vL and 75vR, with average pitch of 70, and with GBFB of 99
Pitcher B (RHP) also has splits of 65vL and 75vR, also average pitch of 70, but GBFB of 0

Pitcher B will give up a higher volume of home runs per 100.0 IP BECAUSE PITCHER B REQUIRES A HIGHER VOLUME OF BATTERS FACED TO ACCUMULATE 100.0 IP. Pitcher A records OUTS at a faster rate because of double-plays!!! Over small sample sizes this isn't necessarily noticeable but the cumulative effect over an entire career is statistically-significant

You will observe that these two end up having the same HR RATE per 100 batters faced, but because pitcher B is facing more batters total, he has a higher VOLUME of HR. Rate and Volume are different things! So I do acknowledge your statement is partially true because yes- low GBFB "give up more HR", but it is not because of the attribute itself, it's a CONSEQUENCE of the attribute being low. It's an effect, not a cause.

I have no intention of arguing with you, mostly because I KNOW I can't find the pitchers I tested over several seasons, but it is because of the attribute. Much like PC, the difference between 20 and 30 is insignificant but 0/30 is noticeable. That said, I will concede two things:
1. My test was a tiny sample size. It included three pitchers(0, 50ish, 90+) with otherwise similar ratings over 300+ innings each.
2. I did not take into account BF or DP. But I can't imagine that 0 faced a hundred more batters than 90+ as their WHIPs were similar while their ERA was not.

https://www.whatifsports.com/hbd/Pages/Popups/PlayerRatings.aspx?pid=5662605

best player I ever drafted after 20 in the draft. Inconsistent AF and I had to break him a few times to get the ratings so high, but he usually ends up at the same place every year.

Posted by MikeT23 on 5/19/2017 1:04:00 PM (view original):
I have no intention of arguing with you, mostly because I KNOW I can't find the pitchers I tested over several seasons, but it is because of the attribute. Much like PC, the difference between 20 and 30 is insignificant but 0/30 is noticeable. That said, I will concede two things:
1. My test was a tiny sample size. It included three pitchers(0, 50ish, 90+) with otherwise similar ratings over 300+ innings each.
2. I did not take into account BF or DP. But I can't imagine that 0 faced a hundred more batters than 90+ as their WHIPs were similar while their ERA was not.

It's not because of the attribute, it's just not.

In my first example, the players were almost identical:
Pitcher A (RHP) has splits of 65vL and 75vR, with average pitch of 70, and with GBFB of 99
Pitcher B (RHP) also has splits of 65vL and 75vR, also average pitch of 70, but GBFB of 0

But consider a different example where
Pitcher A (RHP) has splits of 65vL and 75vR, with average pitch of 60, and with GBFB of 99
Pitcher B (RHP) also has splits of 75vL and 85vR, also average pitch of 70, but GBFB of 0

Pitcher A will give up WAY more home runs, both rate and volume, because he's nowhere near as good. GBFB has absolutely nothing whatsoever to do with causation. VEL and GBFB are simply contributing factors towards ERA, they skew ERA-relative-to-WHIP in one direction or another. Slugging correlates most directly with average-pitch

"2. I did not take into account BF or DP. But I can't imagine that 0 faced a hundred more batters than 90+ as their WHIPs were similar while their ERA was not."
The 0 GBFB gives up more runs because of baserunning. Let's say for example your SP leads off the 6th inning with three consecutive walks.
-Player A (GBFB of 99) inherits three runners and has a certain runs-expectancy that can be mathematically defined. His ability to heavily-skew groundballs severely limits the offense's opportunity to score and helps his own ERA, the previous pitcher's ERA, and the team's ERA as a whole.
-Player B (all other attributes equal except for GBFB of 0) will give up a disproportionately-high volume of "productive outs" aka sac flies, etc and therefore drastically under-performs for the previous pitcher's ERA and the team's ERA.
This is similarly-observed when each player starts the inning and doesn't get pulled, player A can get himself out of those jams while player B does not. This is how Baserunning contributes to ERA.

Posted by MikeT23 on 5/19/2017 9:01:00 AM (view original):
Low GB will lead to excess homers. The really good pitcher is worth having even if it's 0 but you'll always feel disappointed. His ERA won't match his WHIP.

This is why it's important to combine these thoughts into an accurate sentence, where "Low GB will lead to a situation where His ERA won't match [edit: be scaled proportionally to] his WHIP. The really good pitcher is worth having even if it's 0 but you'll always feel disappointed."

Your basic ideas are correct but your methodology is completely wrong, you're disjointing the thoughts when in reality the intro and the conclusion are directly related, but the HR volume is a separate derivative consequence of having to face more batters. Low GBFB contributes to higher ERA alone (NOT HIGHER HR RATE) because a higher percentage of baserunners are scoring. Not because HR. We good on that from now on?

OK, you keep using hypotheticals. I used actual HBD players. It matters and low GB leads to HR at a higher rate.

I don't know how a low GB rate could NOT lead to a higher homer rate...a low GB rate means more FB...correct? Annnd flyballs lead to flyballs over the fence...Now unless I missed it on Sportcenter Ive never seen a grounder home run (has been at some point I'm sure but not normally) So I don't get the argument of how low ground ball rate doesn't lead to more homers.

Kyle Freeman of the Rockies has a 67% ground ball rate and has only given up 0.39 homers per 9 innings this season.. Strohman of Toronto similar numbers.. Rickey Nolasco of LA gives up 48% flyballs as opposed to Freeman and Strohmans 25% rate and has given up 2.6 homers per nine innings...I don't see how higher flyball rate doesn't result in more homers...

When you say that average pitch correlates with SLG, do you actually mean SLG or do you mean pitcher ISO? I can find a lot of minor league pitchers with high average pitch totals and high SLG, because their splits suck and their OAV is high.