The Z Files: The Trade Deadline and Park Factors

Sorry gang, but you're about to get another "trade deadline piece." However, hopefully this will be with a unique twist. As my regular readers know, I'm irrationally fascinated with park factors, deeming them, "A Necessary Evil." That is, park factors are far from perfect, but we're better off incorporating them into analysis than ignoring them.

What follows is a thumbnail sketch describing how the players changing teams the past few days should be affected by their new home venues… at least on paper. Before that will be a general review of park factors, as one of the reasons I'm drawn to them is their influence is often non-intuitive.

1. Park factors are designed to flesh out team bias

On paper, a park factor is independent of the quality of a team's offense or pitching. That said, it isn't always successful, especially if a team is tailored to their home park. A hyperbolic example is Fenway Park. The home run index for lefty swingers is 79, meaning homers are reduced 21 percent compared to a neutral park. The Pesky Pole may only be 300 feet from home plate, but it quickly gives way to the deepest right field in the league. Hypothetically, if the Red Sox lineup was filled with lefties who hit the ball right down the line, the park would appear to play favorably for left-handed batters, but in fact it's a result of a unique lineup, able to take advantage of the quirky dimensions while the visitors don't pull the ball enough. Obviously, Boston's lineup isn't constructed in this manner, but the example helps demonstrate how a team can cater to their park. A practical example is Yankee Stadium with its short right-field porch. Left field is very deep, but the Yankees' lineup has several right-handed sluggers adept at going the other way. As such, the home run index for righties is favorable, but only if you have oppo power. If not, the factor is misleading. The majority of venues are devoid of this concern, but it does help to match up team tendencies on both sides of the ball with the park's dimensions, etc.

2. Home run venues aren't always hitter's parks

This could be the chief misunderstanding, especially relevant when a player switches teams. Many of the smaller venues favor homers but suppress runs since there's less outfield to cover, leading to more flyball outs. That said, it will be interesting to see if this trend holds this season with more runs scoring via the long ball than ever before.

The opposite is also true. Some parks embellish runs but squash power. These are generally large venues where the ball doesn't carry. Some parks, like Coors Field, favors both runs and homers. The reason is the outfield is huge to allow flyball hits, but the ball also carries due to altitude.

Here's a list of the three-year average for the 30 MLB Parks:

Camden Yards (BAL), Guaranteed Rate Park (CHW), Minute Maid Park (HOU), Angels Stadium (LAA), Dodgers Stadium (LAD), Miller Park (MIL), Citi Field (NYM), Yankee Stadium (NYY), Citizens Bank Park (PHI) and Safeco Field (SEA) are all much better for power than runs. Fenway Park (BOS), Kauffmann Stadium (KC) and Oracle Park (SF) hinder power but are much better for runs.

3. Venues affect strikeouts and walks

An underappreciated, and underused, application of park factors relates to how they influence strikeouts and walks. Factors such as batter's eye and foul territory along with some atmospheric conditions affect whiffs and free passes. Here are the current three-year averages for each:

Check out Globe Life Park (TEX). It quells strikeouts while amplifying walks. No wonder it's such a great hitting venue. However, keep in mind the Rangers will be moving into a new venue next season. How it plays is unclear, though the heat will likely aid batters. That said, there's a good chance it doesn't affect pitching the same way the current place does, making Rangers pitchers an intriguing dart throw for 2020 keepers since they're no doubt dirt cheap based on their likely 2019 salaries.

4. Venues don't affect all players the same

Sample size noise aside, a park factor measures an aggregate; individuals may not realize the expected affect. This is primarily relevant when looking at players switching venues, especially with at least one at an extreme. Again, even knowing this, it's best to apply the factor to the new expectations than ignore it.

With that as a backdrop, here is a review of the changes incurred by most of the players donning new uniforms in August. If someone of interest is omitted, please either refer to the above tables or post the name in the comments and I'll provide a quick profile.

Zack Greinke: Other than having to face a designated hitter, which is the primary reason the AL ERA is 4.60 compared to 4.40 in the NL, just about everything about the move from the desert to Houston is not a problem. The sole exception is homers. Minute Maid is superior when it comes to boosting strikeouts, limiting walks and preventing runs. Not to mention, the Astros have a knack for identifying the best part of the pitcher's arsenal and emphasizing it. This will be more apropos in a bit; it isn't as relevant with a veteran of Greinke's ilk.

Trevor Richards and Nick Anderson: Leaving the Aquarium, aka Marlins Park, is a downgrade regardless of the move. That said, Tropicana Field isn't a bad landing spot. In terms of fantasy, The Trop will help strikeouts, which could help Anderson attain elite status.

Nicholas Castellanos: Courtesy of Lord Obvious, the team context is much better for Castellanos. The park, however, is a slight downgrade. The caveat is Wrigley Field is essentially two different venues as it plays differently in the summers, essentially rendering the switch a wash.

Ryne Stanek: A hat-tip to my colleague Tristan H. Cockcroft, who shares this nugget in the upcoming Tout Table (a weekly roundtable where the Tout Wars participants answer a question): "Ryne Stanek is going to become only the second pitcher since the save rule was introduced in 1969 to start at least 20 and save at least eight games in a single season (Tom Gordon, 1997)." He'll be aided by the venue.

Jesus Aguilar: Here's a good example of a player not likely to feel the full effect of the change, but Aguilar does move from one of the best power parks to one of the poorest.

Shane Greene: Unless the switch is extreme, it's fine to minimize the expected effect for relievers, as they're likely to work between 10 and 15 frames in their new digs -- far too small a sample to worry about. That said, Greene's shift is essentially parallel.

Zac Gallen: On paper, the still-developing Gallen will be hurt traveling from South Beach to Arizona. The data on Chase Field with the humidor is still being gathered, though after one season it did what was anticipated; Chase Field hurts homers but it still plays plus for runs.

Aaron Sanchez and Joe Biagini: Here's where Houston's ability to tweak a hurler's repertoire, approach or delivery is intriguing, particularly with Sanchez. Houston is quite adept at maximizing spin efficiency, and Sanchez's curve spin is elite. With respect to the venues, Minute Maid favors power, but if Sanchez can keep the ball in the yard, he'll benefit greatly from its run-suppressing tendency.

Derek Fisher: The Lord Obvious reaction is Fisher's team context takes a hit but he'll enjoy greater opportunity up north. The park is a bit of an upgrade in terms of runs and RBI potential, especially since the Blue Jays lineup is on the upswing.

Corey Dickerson: Not only does Dickerson incur a team context boost, he enjoys a huge upgrade in power potential.

Tanner Roark: The league switch is a bummer, but the park switch is a huge plus, even more so as Roark is a flyball pitcher. Something to watch is whether Roark maintains his elevated punchout rate, as the Great American Ballpark is one of the best venues for strike three.

Mike Leake: The league switch helps, but on paper the change hurts Leake as Chase Field is more run-friendly than Safeco Park.

Scooter Gennett: Blech.

Trevor Bauer: Looking at the park switch for Bauer was the genesis of this piece, as the effect is counter-intuitive. Here's a tweet I posted (note CBP should be GAB):

Not only was I asked about the strikeout factor, the validity of the run factor was called into question as intuitively, Bauer should suffer in the Great American Ballpark. This is a great example of data trumping intuition, as Progressive Field assists runs more then The GAB. The caveat is homers are more prevalent in the Great American Small Park and that's been an issue for Bauer. 

While it's not germane to the park factor focus, another reader commented Bauer will be hurt since he no longer gets to face the soft underbelly of the AL Central. Let's rebut that with

Yasiel Puig: Coming in the opposite direction should ding Puig's power, at least on paper. Not shown above is that home run indices are computed for lefty and righty hitters, and Progressive Field hinders right-handed power. That said, he's not known for hitting cheapies, so don't worry about it too much. Big picture, the move should be beneficial, especially since his strikeouts should fall a bit.

Franmil Reyes: Not getting a couple of trips to Coors Field is a downer, as is the fact Petco Park and Progressive Field are nearly identical for right-handed sluggers. Some assume Reyes gets a decent upgrade. He doesn't.