Josh Naylor & Ryan McMahon – Trade Deadline Movers

We finally got some trade deadline action! Last Thursday, the Mariners acquired Josh Naylor from the Diamondback and then on Friday, the Yankees acquired Ryan McMahon from the Rockies. Let’s dive into the park factors to find out how the trades might affect their offensive results.

Since these are in-season moves, I decided to use current year park factors rather than rolling three-years, as I’m assuming that solely for the remainder of this year, they are more predictable of rest of season factors.

Holy guacamole! This is a near rout, which is pretty unexpected as I had no idea that Chase Field has been so favorable for left-handed hitters this year.

Anyway, let’s begin with the hit type factors. Chase Field runs away with the non-home run factors and none of the battles are particularly close. Because singles are most plentiful, those factors are most important, and T-Mobile ranks just 23rd in baseball in the factor. Chase has been excellent across the board and sure enough, Naylor has posted a .335 BABIP at home, versus just a .285 mark on the road. Then again, that road BABIP is almost identical to his career BABIP of .287, suggesting that he has really benefited from Chase’s friendly confines. That’s bad news for Naylor’s BABIP in Seattle, which could result in his mark dropping back toward his career average, causing his batting average to tumble.

The triples factor doesn’t mean anything here as Naylor has recorded just two over his entire career, but man the difference between the two factors is crazy!

Moving onto the home run factors, we find T-Mobile’s only win. While it’s a meaningful improvement, it’s interesting to see that both parks have dramatically suppressed left-handed home runs this year. He goes from the 24th ranked park in left-handed home run factor to the 18th. Once again, his 2025 splits support the factors, as he posted just a 7.4% HR/FB rate at home this year versus a 12.5% mark on the road. He’s clearly in a bit of a better spot now for home runs, but not significant enough to believe he’ll gain more than a homer or two from the park switch.

We next slide on over to the walk and strikeout factors, where T-Mobile continues to lose the head-to-heads. Both parks suppress walks, but T-Mobile does so more meaningfully. Although Chase was nearly neutral for walks, Naylor actually recorded a higher walk rate on the road. He’ll likely continue to do so in Seattle, and the low walk rate factor could affect his OBP and ultimately his runs scored total. T-Mobile is actually perfectly neutral for strikeouts, while Chase suppressed them. Naylor posted a much lower strikeout rate at home than on the road and so far he has actually posted the lowest strikeout rate of his career, ignoring the same sample 2020 season. That’s really surprising given that his SwStk% has also jumped to a career worst, continuing a trend of increasing marks for three straight seasons now. I’m guessing his strikeout rate jumps over the rest of the season.

Finally, we get o both the runs scored and overall park factors, which T-Mobile trails dramatically in. In fact, T-Mobile ranks tied as the worst park in the majors in runs scored and overall park factors. That ain’t good for a player joining that offense!

It’s pretty clear that from a park factor standpoint, Naylor takes a hit. The park could reduce his BABIP and walks, while increasing his strikeouts, all of which will only be marginally offset by a higher home run factor. He’s also not even going to a better offense, as the two teams actually posted identical wRC+ marks, though obviously the Diamondbacks mark benefited from Naylor’s presence. He’ll also be behind slightly worse OBP marks and Cal Raleigh might end up taking away from RBI opps if his home run pace doesn’t slow down!

It’s always fun to see a career Rockies hitter joining a new team. We know Coors Field has consistently been a premier hitter’s park, so the conventional wisdom is that former Rockies are going to immediately bust on their new teams. This is especially true given the sometimes huge home/road splits these hitters have, as the thin air in Colorado makes it more difficult to adjust to pitches on the road. Now, we’ll get to see another hitter, though two months is hardly enough of a sample to really conclude anything.

As expected, Coors Field wins most of the factors, though Yankee Stadium does collect two wins.

Coors Field is the best hits-boosting park in baseball for left-handers. It boosts all hit types as the second best park for singles, and strong factors for doubles and triples as well. It’s therefore fantastic for BABIP. Over his career, McMahon has posted a .332 BABIP at home and .293 on the road. For as good as Coors is for hits, Yankee might be similar in the opposite direction, as it suppresses all hit types rather significantly. It’s actually the second worst park for left-handed singles! Who knew?! McMahon’s BABIP sits at the second lowest of his career, with only the short 2020 season coming in lower. So he might not actually suffer a hit here as we may have expected a rebound over the rest of the season. Now though, that rebound is going to be more challenging.

Moving onto home runs, we know that Yankee is a top tier home run park for left-handers. This year, it ranks third best in baseball, with Coors coming in at seventh. But the ordinal rankings don’t matter as much as the absolute factors and a 15 point difference here is pretty big. Over his career, McMahon has posted a 22.4% HR/FB rate at home, versus a 14.2% mark on the road, so he has really liked Coors for home runs. The issue here is that he hasn’t been a pulled fly ball guy over his entire career, though he’s currently sporting his highest mark, but that’s still below league average. Since Yankee Stadium is not as beneficial for right-handed home runs this year, he might not actually experience the full increase in left-handed home run factor.

Next up are the walk and strikeout factors, where it’s a split decision. Yankee has easily been the best park in baseball for walks, while Coors ranks third. McMahon has always had good plate patience, now having posted four straight double digit marks, and his current mark represents a career best. So this move should be good for his walk rate, benefiting his runs scored total.

Strikeouts are a different story. Coors has been the third toughest park to strike out in, while Yankee has been closer to neutral, though the park still has suppressed punchouts. McMahon is a big strikeout guy and has predictably struck out more on the road in his career, though the gap isn’t as big as I would have guessed. Moving out of Coors should definitely increase his strikeouts, which are already at a high level over 30%. That’s not a good sign for his batting average.

Finally, both the runs scored and overall park factors favor Coors, though Yankee is definitely a good park for left-handed hitters. Ignoring team context, the move is a clear negative for McMahon’s fantasy value. Also hurting here is that he’ll likely be platooned, cutting into his counting stats, and he’s hitting near the bottom of the lineup, also cutting into his plate appearances, and resulting counting stats.