Eduardo Rodriguez Signs With Diamondbacks

Last week, left-handed starter Eduardo Rodriguez signed a four-year, $80 million contract with the Diamondbacks, ending his two-season stay in Detroit. After posting the lowest ERA of his career, let’s consult the park factors to figure out whether the change in park might impact his results.

These factors are pretty darn close! Unlike for hitters, we don’t need to break out the specific righty or lefty factors for the hit types, as we could just look at the overall factors, making the comparison easier.

Let’s begin with the hit type factors. It’s a mixed bag here with Chase Field slightly more hitter friendly than Comerica for singles, as both inflate the hit type. Despite Comerica’s singles inflating ways, Rodriguez actually posted a lower BABIP there over the last two years, but also posted better than league average marks both home and on the road. He has actually posted career best BABIP marks the last two seasons, which differs dramatically from his career mark, which stands just over .300. Either he’s been quite fortunate these past two years, he has figured out something to reduce hits on balls in play, his defensive support has been fantastic, or a combo of these three. It’ll be interesting to see where his BABIP goes now in a new park and with a new fielding unit behind him.

Chase also inflates doubles versus a neutral factor at Comerica, which is a negative for Rodriguez’s ISO against. It’s only partially offset by the big gap in triples factor, since the hit type is so infrequent to begin with. Comerica was the best park in baseball this year for triples, but Chase was actually fourth best! So they are seemingly close if just looking at rankings, but Chase was so good that there’s still a wide gap. Either way, with so few triples, perhaps this only reduces his triples against by one or two, and those might merely become doubles anyway.

Last in the hit type factors is home runs. Lucky for him, he’s moving from a park that ranks tied for sixth toughest to homer in and moves to one that’s third toughest! It’s not often you move from one extreme environment into an even more extreme one. Rodriguez has posted a 1.5% lower HR/FB rate at home during his time with the Tigers, and has been pretty league average in the metric throughout his career, but is coming off a career best. Interestingly, he has been remarkably consistent, considering how much luck is involved in the metric, as he has remained in the low teens, with a mark no higher than 13.3%, for the majority of his career. I wouldn’t expect anything lower than he posted this season, but the move should help ensure he keeps his HR/FB rate around his career average at the very least.

Moving along to the strikeout and walk factors, we find that Chase is neutral for strikeouts and slightly reduces walks, both of which are slightly more pitcher friendly than the factors at Comerica. Rodriguez has actually posted a higher strikeout rate and significantly lower walk rate on the road compared to Comerica these past two seasons, which directionally matches the factors, but the magnitude of the difference is greater than the factors would suggest. So perhaps he was hampered more by his home park than the average bear. His last two season strikeout rates were his lowest since 2016, so maybe the park switch could trigger somewhat of a strikeout rate rebound.

Next up are the batted ball type factors, which suggest more grounders, and fewer fly balls and pop-ups. The IFFB factors are significantly different, with Comerica ranking second among parks, while Chase ranked sixth toughest to hit a pop-up. That’s a large swing, and sure enough, Rodriguez’ IFFB% at Comerica was nearly double what it was on the road. These factors already impact the hit type factors, but it seems pretty clear that Chase is a bit worse for his BABIP, inflating it moreso than Comerica.

Finally, we finish with the FIP and Basic factors. FIP suggests both are pitcher’s parks, likely given the low home run factors, with Chase even friendlier, again, because of the even lower home run factor. But the Basic factor suggests both parks are perfectly neutral.

Overall, the factors suggest Rodriguez’ BABIP might increase, while his HR/FB rate might decrease. They are generally pretty similar, though, so I wouldn’t expect a meaningful impact on his results and fantasy value solely from the switch in home park.