HR Park Factors: Does This Make Sense?

kq76 · 10-26-2021, 04:46 PM

I noticed the 3-year HR vL park factors for Rogers Centre is 135 while vR it's only 105. I thought, huh, that's weird, I thought its dimensions were all symmetrical. I check and they are. So I thought, oh, well it must have not separated Sahlen and Dunedin. But no, it looks like it does as there's no 2020 data (they didn't play in Toronto last year). Okay, so, it must be something else then. Maybe they've got some sort of wind tunnel going on.

Whatever is going on you'd think management would take advantage of this and bring in some lefty power bats. In fact, they have no power lefties!

Then I noticed the HR vL data varies wildly from year to year. In fact, in the last 20 years, it's been as high as 139 to as low as 87! And I was wondering, is this normal? Does this mean we really shouldn't put too much into park factors?

One might say it's just vL factors we can't put too much into because there's so few lefties, but the vR factors vary wildly from year to year too!

And yeah, sure, there'd be some if they changed the dimensions somehow, but these factors go back and forth and, if they did make some changes, I doubt they made that many from year to year.

Brad K · 10-27-2021, 01:37 AM

I've been wondering, do park factors most often measure players or luck? Not weather, in this case. I suspect their measurement of park factors is in the minority.

monkeyman576 · 11-01-2021, 05:17 PM

In the last 10 years, Rogers Center has 5 seasons of a park factor v L(HR) over 120 and 4 years of a park factor v L(HR) under 100. Looking at the trends across MLB as a whole for those years, there does not seem to be a significant correlation between the HR rates for the seasons and the park(i.e. sometimes HR's were down for the season for MLB but up for Rogers Center). So I would say that Rogers Center is a statistical anomaly where the park factors fluctuate on a yearly basis for no apparent reason.

RchW · 11-01-2021, 06:22 PM

You'd have to check games with the dome open v closed where it is typically easier to hit HR when closed. Even that's not simple because when it's open in gusty wind days I've seen balls hit high knocked down and over from the LF line to the alley in LCF.

The dome home plate faces North. This is unusual in MLB. Predominant wind is from W to SW ie towards RF which may explain higher LHB factors but I have no way to quantify that.

It seems to me PF for the dome should be at least grouped by dome open/closed status at game time.

Also for other PF the dome playing surface has changed radically. The early turf was thin and laid directly on concrete with only dirt cut outs at the bases. That produced plenty of GB doubles and triples to add onto line drives into the gaps. Currently the infield is a full dirt style and the new turf is tuned to perform like grass fields and is much softer with more predictable bounces.

FWIW

dsvitak · 11-06-2021, 12:15 AM

Quote:

Originally Posted by RchW

You'd have to check games with the dome open v closed where it is typically easier to hit HR when closed. Even that's not simple because when it's open in gusty wind days I've seen balls hit high knocked down and over from the LF line to the alley in LCF.

The dome home plate faces North. This is unusual in MLB. Predominant wind is from W to SW ie towards RF which may explain higher LHB factors but I have no way to quantify that.

It seems to me PF for the dome should be at least grouped by dome open/closed status at game time.

Also for other PF the dome playing surface has changed radically. The early turf was thin and laid directly on concrete with only dirt cut outs at the bases. That produced plenty of GB doubles and triples to add onto line drives into the gaps. Currently the infield is a full dirt style and the new turf is tuned to perform like grass fields and is much softer with more predictable bounces.

FWIW

Stadium design and atmospheric effects are HUGE when evaluating a park for HR tendencies.

I lived in central California from 1963 to 1971, and saw dozens of games at the old Candlestick Park in San Francisco. At night, the winds would blow in from right field at a steady 15-25 mph, sustained, almost every night, with higher gusts.

I saw Willie McCovey hit a ball way over the fence in right, and it got blown all the way back to second base. Put McCovey in Yankee stadium, and he hits 60 or more, more than once. Easy.

Brad K · 12-05-2021, 04:05 PM

People think park factors for home runs measure how hard or easy it is to hit home runs in a particular park. They don't. Park factors measure how many home runs were hit there compared with other parks. How many home runs were hit in a park doesn't necessarily have a direct linear relationship to how hard it is to hit home runs in a park.

The huge variability in park factors from year to year for the same park shows that a large part of what they're measuring is not what their name implies.

mytreds · 12-05-2021, 05:39 PM

Quote:

Originally Posted by Brad K

People think park factors for home runs measure how hard or easy it is to hit home runs in a particular park. They don't. Park factors measure how many home runs were hit there compared with other parks. How many home runs were hit in a park doesn't necessarily have a direct linear relationship to how hard it is to hit home runs in a park.

The huge variability in park factors from year to year for the same park shows that a large part of what they're measuring is not what their name implies.

Well said Brad o/

mytreds · 12-05-2021, 05:42 PM

Quote:

Originally Posted by dsvitak

Stadium design and atmospheric effects are HUGE when evaluating a park for HR tendencies.

I lived in central California from 1963 to 1971, and saw dozens of games at the old Candlestick Park in San Francisco. At night, the winds would blow in from right field at a steady 15-25 mph, sustained, almost every night, with higher gusts.

I saw Willie McCovey hit a ball way over the fence in right, and it got blown all the way back to second base. Put McCovey in Yankee stadium, and he hits 60 or more, more than once. Easy.

Poor Horace Stoneham was shown the proposed ballpark site in the mid-morning, where it is sunny, clear and quite pleasant. He of course gave the fated contract to build the stadium a green light based on the fact he wasn’t shown the conditions of candlestick point at night. Candlestick would doom the Giants franchise for years to come based on this oversight.

dsvitak · 12-06-2021, 02:12 PM

Quote:

Originally Posted by RchW

You'd have to check games with the dome open v closed where it is typically easier to hit HR when closed. Even that's not simple because when it's open in gusty wind days I've seen balls hit high knocked down and over from the LF line to the alley in LCF.

The dome home plate faces North. This is unusual in MLB. Predominant wind is from W to SW ie towards RF which may explain higher LHB factors but I have no way to quantify that.

It seems to me PF for the dome should be at least grouped by dome open/closed status at game time.

Also for other PF the dome playing surface has changed radically. The early turf was thin and laid directly on concrete with only dirt cut outs at the bases. That produced plenty of GB doubles and triples to add onto line drives into the gaps. Currently the infield is a full dirt style and the new turf is tuned to perform like grass fields and is much softer with more predictable bounces.

FWIW

At that latitude, only the months of July and August would have prevailing winds with a southerly component. All other months would see west or northwesterly winds, on average.

This is also why the Cubs' offense shuts down the first of September..the mean position of the polar front slides to their south, and winds start coming in from right and right center.

Westheim · 12-08-2021, 03:03 AM

Quote:

Originally Posted by dsvitak

At that latitude, only the months of July and August would have prevailing winds with a southerly component. All other months would see west or northwesterly winds, on average.

This is also why the Cubs' offense shuts down the first of September..the mean position of the polar front slides to their south, and winds start coming in from right and right center.

Is something like that the reason why the Mets can't hit any time of year, every year?

Except for Pete. Weather does not matter for Pete - he is the mightier force of nature.

Syd Thrift · 12-08-2021, 09:41 AM

How a park compares with other parks in the league can be a big deal too, perhaps not as much with 15 parks per league but still big. The best examples you’ll see come in the 16 teams in 10 cities era where AL and NL teams shared parks. Sportsman’s Park in St. Louis for instance was consistently pretty neutral in the NL (I think it trended towards hitters but didn’t really favor lefties or righties) but in the AL it favored RHB pretty heavily. Why? A big part of that was that it wasn’t Yankee Stadium. There were other parks in the AL that had longer LF fences than RF ones - Griffith Stadium was one, IIRC - and this meant that a stadium with relatively equal dimensions was a “right handers park” so to speak.

10-26-2021, 04:46 PM	#1
kq76 Global Moderator Join Date: Nov 2002 Location: Vancouver, Canada Posts: 11,488	HR Park Factors: Does This Make Sense? I noticed the 3-year HR vL park factors for Rogers Centre is 135 while vR it's only 105. I thought, huh, that's weird, I thought its dimensions were all symmetrical. I check and they are. So I thought, oh, well it must have not separated Sahlen and Dunedin. But no, it looks like it does as there's no 2020 data (they didn't play in Toronto last year). Okay, so, it must be something else then. Maybe they've got some sort of wind tunnel going on. Whatever is going on you'd think management would take advantage of this and bring in some lefty power bats. In fact, they have no power lefties! Then I noticed the HR vL data varies wildly from year to year. In fact, in the last 20 years, it's been as high as 139 to as low as 87! And I was wondering, is this normal? Does this mean we really shouldn't put too much into park factors? One might say it's just vL factors we can't put too much into because there's so few lefties, but the vR factors vary wildly from year to year too! And yeah, sure, there'd be some if they changed the dimensions somehow, but these factors go back and forth and, if they did make some changes, I doubt they made that many from year to year. __________________ My OOTP Wishlist \| My FAQ List OOTP Wiki \| Your Recommended Team Nicknames, By City (A Crowdsourced Project)

10-27-2021, 01:37 AM	#2
Brad K Hall Of Famer Join Date: May 2016 Location: St Petersburg Florida USA Posts: 6,321	I've been wondering, do park factors most often measure players or luck? Not weather, in this case. I suspect their measurement of park factors is in the minority. __________________ Pirates Play Moneyball 1951 to 2008 46,000 views and counting!... Wow, up to 47,000, thank you. Wow, I hadn't checked for weeks. Oct 9 2024 its 79,561. Why do people use different players, different lineups, different strategy, development, talent change randomness, and the development lab, but judge the game on whether it produces historical statistics?

11-01-2021, 06:22 PM	#4
RchW Hall Of Famer Join Date: Jul 2004 Location: Toronto ON by way of Glasgow UK Posts: 15,629	You'd have to check games with the dome open v closed where it is typically easier to hit HR when closed. Even that's not simple because when it's open in gusty wind days I've seen balls hit high knocked down and over from the LF line to the alley in LCF. The dome home plate faces North. This is unusual in MLB. Predominant wind is from W to SW ie towards RF which may explain higher LHB factors but I have no way to quantify that. It seems to me PF for the dome should be at least grouped by dome open/closed status at game time. Also for other PF the dome playing surface has changed radically. The early turf was thin and laid directly on concrete with only dirt cut outs at the bases. That produced plenty of GB doubles and triples to add onto line drives into the gaps. Currently the infield is a full dirt style and the new turf is tuned to perform like grass fields and is much softer with more predictable bounces. FWIW __________________ Cheers RichW If you’re looking for a good cause to donate money to please consider a Donation to Parkinson’s Canada. It may help me have a better future and if not me, someone else. Thanks. “Conservatism consists of exactly one proposition …There must be in-groups whom the law protects but does not bind, alongside out-groups whom the law binds but does not protect.” Frank Wilhoit

12-05-2021, 04:05 PM	#6
Brad K Hall Of Famer Join Date: May 2016 Location: St Petersburg Florida USA Posts: 6,321	People think park factors for home runs measure how hard or easy it is to hit home runs in a particular park. They don't. Park factors measure how many home runs were hit there compared with other parks. How many home runs were hit in a park doesn't necessarily have a direct linear relationship to how hard it is to hit home runs in a park. The huge variability in park factors from year to year for the same park shows that a large part of what they're measuring is not what their name implies. __________________ Pirates Play Moneyball 1951 to 2008 46,000 views and counting!... Wow, up to 47,000, thank you. Wow, I hadn't checked for weeks. Oct 9 2024 its 79,561. Why do people use different players, different lineups, different strategy, development, talent change randomness, and the development lab, but judge the game on whether it produces historical statistics?

11-01-2021, 05:17 PM	#3
monkeyman576 Hall Of Famer Join Date: Jun 2010 Posts: 3,328	In the last 10 years, Rogers Center has 5 seasons of a park factor v L(HR) over 120 and 4 years of a park factor v L(HR) under 100. Looking at the trends across MLB as a whole for those years, there does not seem to be a significant correlation between the HR rates for the seasons and the park(i.e. sometimes HR's were down for the season for MLB but up for Rogers Center). So I would say that Rogers Center is a statistical anomaly where the park factors fluctuate on a yearly basis for no apparent reason.