Not all Class A Advanced leagues are created equal.
Toolshed's 2019 series on park factors has already explored Triple-A and Double-A and now moves to the Minors' third-highest level, one that comes with a some wide variance. It's well known that the California League is where hitters go to flourish and the Florida State League is where pitchers can thrive. But this is especially important to keep in mind here because what looks like a hitters' park in the Florida State League wouldn't necessarily be a hitters' park by California League standards. However, the park-factor formula here is only used to compare stadiums in their own league. So, while Bradenton and Lancaster both look like places sluggers can lift off with regularity based on their park factors, 212 homers were hit in Lancaster this season while only 119 were hit in Bradenton. 
First consider the following table for context. (Each league's rank among the 16 domestic Minor League circuits is in parentheses.)

League	R/9	HR/9	H/9
California	4.8 (seventh)	0.8 (sixth)	8.6 (fifth)
Carolina	4.3 (12th)	0.6 (10th)	8.2 (11th)
Florida State	4.1 (16th)	0.6 (12th)	8.2 (10th)

As expected, the California League remains a good league for hitting, though not as much as when Bakersfield and High Desert were still in the fold. It still sees about one-third more homers than its Class A Advanced counterparts, and full nine-inning games in the Cal League typically have 1.4 more runs scored than they do in the FSL.
Now on to the individual circuits. A reminder that each park factor is put on a scale in which 100 is considered average. Anything above that favors hitters. Anything below makes the park more pitcher-friendly in that category.

California League -- 2019

Team	R	HR	H
Lancaster	150	181	133
Stockton	101	144	94
Rancho Cucamonga	101	95	100
San Jose	99	100	100
Visalia	96	104	93
Modesto	90	53	96
Inland Empire	87	73	98
Lake Elsinore	76	63	87

California League -- 2017-19

Team	R	HR	H
Lancaster	145	179	124
Rancho Cucamonga	106	106	105
Visalia	101	109	98
San Jose	95	99	95
Stockton	94	137	95
Modesto	92	54	97
Inland Empire	87	74	93
Lake Elsinore	82	58	94

Again, no big surprises. The Hangar remains an absolute launching pad.
As mentioned, 212 home runs were hit in Lancaster this season, most among all Class A Advanced parks. Of the 908 homers hit in the Cal League in 2019, 23.3 percent were at The Hangar. The next closest in the Cal League was Stockton, which saw 137 balls leave the yard. While that may seem like an outlier, the three-year model shows that Lancaster's 2019 homer factor is trending only slightly from its typical standards -- 181 vs. 179. Make sure to pour one out for Lancaster pitchers, who have to call the windy confines of The Hangar home. JetHawks pitching staffs have given up the most homers in the Cal League in each of the last four seasons. The last time they didn't was in 2015, when they allowed the second-most behind now-defunct High Desert. In 2019 alone, the JetHawks had a collective 5.36 ERA. Since 2010, there have been only three seasons in which the club didn't post an ERA above 5.00. So while it's great that Lancaster batters can tee off -- which they did in 2019 with six JetHawks ranking among the top 13 in the Cal League in slugging percentage -- remember how tough Rockies pitching prospects have it.
At the other end of the spectrum, Lake Elsinore and Modesto must each feel like welcome sights for pitchers trekking across the California League, especially those who call those places home. Storm pitchers led the Cal League with a 3.34 ERA in 2019 -- two full runs lower than Lancaster's ERA -- while Modesto placed second at 3.68. Home runs were a big reason there. The parks at Modesto (68) and Lake Elsinore saw about one-third as many homers as Lancaster did.

Prospects affected:

Ryan Rolison: The Rockies' top pitching prospect is a pretty clear example why some farm systems have chosen to have their pitchers skip Lancaster entirely. MLB.com's No. 84 overall prospect breezed through three starts with Class A Asheville before jumping to Lancaster in late April, and that's when he was met with some pretty severe splits. His road numbers were solid: 3.35 ERA, 1.00 WHIP, .215 average-against, eight homers allowed in 51 innings away from Lancaster. At the home of the JetHawks, those numbers flew north -- 6.06 ERA, 1.78 WHIP, .320 average-against and 14 homers in 65 1/3 frames. Rolison has the deep arsenal and control to stick as a starter, and as these numbers show, fans shouldn't get discouraged by his 4.67 ERA over 22 starts in the Cal League in his first full season.

Joe Rizzo: Jarred Kelenic was the more notable Mariners prospect to spend the bulk of his season at Modesto, but to his credit, his home-road splits weren't extreme enough for consideration here. Instead, turn to Rizzo, the 2016 second-rounder and Seattle's No. 19 prospect. The 21-year-old corner infielder was held at Modesto for a second straight season and saw some solid gains, finishing with a .295/.354/.423 line and 10 homers in 129 games. But it would have been interesting to see what those improvements could have done away from John Thurman Field. Seven of Rizzo's 10 homers were hit on the road, where he slugged .464 compared to .374 at home. That said, things won't get easier for him when he heads to Arkansas in 2020 -- home of Double-A's most pitcher-friendly park.

MacKenzie Gore: Gore's video-game numbers (1.02 ERA, 0.71 WHIP, 110 strikeouts in 79 1/3 innings) in the Cal League were good enough to win him a MiLBY, and for those looking at Lake Elsinore's park factors and thinking he may have gotten an advantage, think again. Gore's stats at home with the Storm were incredibly good -- 1.29 ERA, 0.62 WHIP, .142 average-against in 42 innings. But his road numbers were right there and even better in some areas -- 0.72 ERA, 0.80 WHIP, .132 average-against. What's more, the 20-year-old left-hander served up four homers at home but didn't give up any on the road despite making one start in Lancaster and three more in Rancho Cucamonga -- another reason to get excited about the future of MLB.com's No. 4 overall prospect.

Carolina League -- 2019

Team	R	HR	H
Carolina	118	143	109
Winston-Salem	118	148	109
Frederick	114	138	103
Fayetteville	108	108	101
Salem	100	69	114
Lynchburg	98	79	103
Down East	97	128	99
Potomac	89	83	91
Myrtle Beach	86	76	89
Wilmington	78	50	84

Carolina League -- 2017-19

Team	R	HR	H
Frederick	116	165	105
Winston-Salem	116	136	109
Fayetteville '19	108	108	101
Carolina	106	111	107
Salem	100	81	106
Lynchburg	98	76	99
Down East	97	121	97
Potomac	94	97	95
Myrtle Beach	93	86	99
Buies Creek '17/18	93	79	90
Wilmington	82	53	90

Alright, back to the purpose of this column -- to find out something new.
The three-year window used here is actually one of the most interesting in recent Carolina League history. As mentioned, High Desert and Bakersfield both closed up shop in the California League following the 2016 season, only to be replaced by new clubs in the Carolina League the following year. Down East immediately moved into Grainger Stadium (former home of the Kinston Indians) and has been there ever since. The other club had a slightly more complicated move.
The Astros first moved their Class A Advanced affiliate to Buies Creek, North Carolina, where it temporarily played for two seasons at Jim Perry Stadium on the Campbell University campus. In 2019, the move became permanent when Astros Minor Leaguers settled into Fayetteville and brand-new Segra Stadium. The park factors for both Jim Perry Stadium (two seasons) and Segra Stadium (one season) are included in the chart above to cover all bases.
So what happened? Well, Fayetteville brought a little more offense to the Carolina League. Runs allowed at the home of the Astros affiliate jumped from 529 in 2018 to 618 this past season, while home runs saw a similar uptick from 82 to 106. Part of the explanation is a move to comfier dimensions. Jim Perry and Segra are actually pretty similar everywhere except right-center with the former sitting 375 feet from home and the latter much closer at 357. Add in a wind that occasionally blows toward the outfield, and there are good factors for some relatively high-scoring games. It'll be interesting to see if and how that continues as the sample expands in Fayetteville in 2020, when the Carolina League will be adding another new stadium in Fredericksburg as well.
Prospects affected

Seth Beer: Staying with Fayetteville here for a moment, Beer entered his first full season with many knowing it would be his bat that would carry him through the Astros system, at least at first. He showed off how advanced that bat could be first with the Woodpeckers, specifically at home. Beer played 15 games at Segra Stadium and hit six homers while slugging .750. He went deep three times and posted a .486 slugging percentage in 20 games on the road in the Carolina League. Seeing how dominant he was looking with Fayetteville, the Astros promoted Beer to Double-A Corpus Christi in mid-May. He was traded to the D-backs two months later in the Zack Greinke deal.

MJ Melendez: If not for the presence of a new stadium, Wilmington's continued existence as a pitching haven would be the story here. Several of the Royals top arms passed through Delaware at various points of 2019, but it's worth pointing out how one of Kansas City's most promising position-player prospects might have been set back by his turn in Wilmington. Melendez hit 19 homers and posted an .814 OPS at Class A Lexington during his first full season in 2018. This season, those numbers dropped to nine and .571. The 20-year-old backstop didn't exactly post eye-popping stats on the road in the Carolina League either, but his home splits were notable for all the wrong reasons -- .133/.248/.243, three homers, 13 total extra-base hits in 56 games. Melendez only turns 21 in November, so it's worth wondering whether he should return to Class A Advanced for another season to work on his offensive game. Then again, given the conditions in Wilmington, maybe it's best to get him away instead.

Miguel Amaya: To a less extreme degree, Myrtle Beach also favors pitchers, making an interesting testing ground for another 20-year-old catcher. Amaya, the Cubs' No. 2 prospect, hit seven of his 11 home runs with the Pelicans on the road, despite playing seven fewer games there, and slugged 111 points higher (.458 vs. .347) away from Myrtle Beach. Compare that to league home run leader Mario Feliciano (19), who went deep 14 times at home but managed to slug only .395 away from Carolina, and you'll see why Amaya might still have the higher offensive ceiling despite the lower numbers in the same circuit.

Florida State League -- 2019

Team	R	HR	H
Dunedin	124	144	116
Clearwater	114	110	108
Bradenton	110	148	99
Tampa	109	110	103
St. Lucie	106	119	112
Charlotte	101	97	99
Daytona	98	129	92
Fort Myers	96	71	98
Florida	93	74	93
Jupiter/Palm Beach	89	67	96
Lakeland	74	78	91

Florida State League -- 2017-19

Team	R	HR	H
Dunedin '19	124	144	116
Bradenton	113	150	101
St. Lucie	112	110	107
Daytona	111	138	102
Fort Myers	107	98	103
Tampa	106	117	103
Dunedin '17/18	106	113	105
Clearwater	100	109	97
Florida	99	81	101
Charlotte	98	74	100
Jupiter/Palm Beach	82	61	94
Lakeland	81	83	91

Another interesting wrinkle featuring a Class A Advanced park in the FSL.
Dunedin was undergoing renovations to its stadium -- which will be called TD Ballpark starting in 2020 -- this past season, meaning the Jays had to move their Class A Advanced affiliate to Jack Russell Memorial Stadium in Clearwater. Once Spring Training home to the Phillies, Jack Russell is now primarily used for the Clearwater High School and St. Petersburg College baseball teams. Professional hitters sure treated it like it was designed for lesser competition. Blue Jays hitters especially took advantage, hitting 49 homers in 66 home games compared to only 27 on the road. (Note: Dunedin did play six "home" games on the road -- four in Clearwater, one in Bradenton, one in Daytona -- but these weren't considered large enough to affect the larger park factors over the full season.) When Blue Jays prospects head back to Dunedin next spring, they'll likely still find a hitter-friendly stadium -- one that posted above-average marks in all three park factors in 2018 and 2017 before the temporary move -- but they aren't likely to find anything like Jack Russell.
One other thing to note with the above table is that the raw numbers for both Jupiter and Palm Beach have been combined because they share Roger Dean Chevrolet Stadium, thus spitting out park factors for one single park. It should be noted that this data isn't perfect. Because of the nature of splits, a game in which Palm Beach hosted Jupiter still counted as a road game for Jupiter, thus skewing the numbers slightly since the game didn't technically happen away from Roger Dean. That said, the numbers still show that the shared park is one of the most pitcher-friendly, not only in the FSL but in the grand scheme of the Minors as well.
Prospects affected:
Trevor Rogers: Sticking with Jupiter, Rogers enjoyed a breakout season that saw him earn FSL mid- and end-of-season All-Star honors, and putting him here isn't meant to take away from his accomplishments by any means. But the Marlins' No. 8 prospect enjoyed his home cooking in 2019. Rogers posted a 1.94 ERA, 0.94 WHIP and .207 average-against in 51 innings at home with Jupiter, compared to 3.03, 1.23 and .251 in 59 1/3 frames on the road. In a slight reversal, he did allow more homers at home -- four over three -- but the overall numbers still paint a picture. Keep an eye on the 2017 first-rounder as he enters the upper Minors for good in 2020.

Mason Martin: After Martin hit 23 homers in 82 games with Class A Greensboro, there was some worry that the FSL would stifle his breakout. Because of his home environment in Bradenton, that ended up not being the case. Martin went deep seven times in only 21 games during his time with the Marauders, slugging .640 and producing a 1.019 OPS in that span. While he still went deep five times in 28 games on the road, his slugging percentage and OPS fell to .446 and .744, respectively, in 28 games played away from Bradenton. Martin assuredly deserves credit for hitting 35 total homers in a year he partially spent in a pitchers' league, but it appears LECOM Park sands away some of that credit.
Tarik Skubal: Speaking of breakouts, the 2018 ninth-rounder exhibited one of the biggest in the Minors in his first full season, mostly on account of something that rarely relies on park factors -- the strikeout. (Skubal fanned 179 batters in 122 2/3 innings between Lakeland and Double-A Erie, third-most in the Minors.) But when Skubal did allow FSL hitters to put the ball in play, he seems to have gotten a boost from some friendly confines in Lakeland. The 22-year-old southpaw posted a 1.70 ERA, 0.88 WHIP and .185 average-against in 47 2/3 innings at Publix Field at Joker Marchant Stadium but saw those rise to 3.86, 1.19 and .242 at home. What's more, all five of his homers allowed in the FSL came away from Lakeland. Then again, if Skubal can manage to keep up his 36.5 percent strikeout rate from 2019, none of his future parks will factor much into his performance anyway.