[Splitter24]

There were 26% more home runs hit in the 2018 AL (Severino's league) vs. the 2012 NL (Dickey's league). Severino gave up 10% more HR than Dickey, but in an environment where HR's were 26% more likely to occur. So it only makes sense that Severino's Movement is higher.

Taillon allows about 3% fewer home runs than Dickey in a league where HR's are 17% higher than Dickey's league. Same story here.

I'm not sure precisely how the Movement stat is calculated. But it makes complete sense that Severino's and Taillon Movement ratings should be roughly 15% better than Dickey's if you make adjustments for the league in which they were playing. And that's not even adjusting for ballpark factors. According to 2018 data, Citi Field was the toughest ballpark to homer in. PNC was a little easier at #25. Yankee Stadium came in at #6. So the ballpark data also points to Dickey playing in a park that helps him prevent HR's and to a slightly lesser extent for Taillon, while Severino plays in a homer friendly environment that makes his HR allowed more impressive.