Eddie Rosario Remains in AL Central, Signs With Indians by Mike Podhorzer February 1, 2021 On Friday, it was reported that Eddie Rosario, career Minnesota Twin, had signed a one-year contract with the division rival Indians. Is there a strong perception about either of these parks and their affects on offense? I don’t think so, unless you’re super familiar with park factors. However, just because it’s more difficult to guess off the top of our head like Yankee Stadium’s home run boosting power, doesn’t mean there’s no change in factors. So let’s consult them and see how Rosario’s offense might be affected. Park Factor Comparison Team 1B as L 2B as L 3B as L HR as L SO BB GB FB LD IFFB Target Field (Twins) 102 102 112 97 100 101 101 100 101 99 Progressive Field (Indians) 101 107 87 104 100 100 101 95 101 93 SOURCE: FanGraphs.com As a reminder, all park factors are halved, to account for only half the games being played at home. Let’s begin with the hit type factors, which are displayed for only left-handed hitters, the side of the plate Rosario hits from. We find that both parks slightly boost singles, with Progressive marginally less so. Since singles are the most common hit type, they have the greatest influence on BABIP among all hit types. After four straight seasons with BABIP marks over .300, Rosario has seen that mark plummet, first to .273 in 2019, and then all the way down to jus .248 during last year’s short season. Some of the reasons for the decline include becoming an extreme fly ball hitter and grounding into the shift more and more frequently. Clearly Rosario could use a park good for singles, but he’s actually leaving one that’s slightly better for them, so that’s no good. It’ll be up to him then to avoid those shifted defenders and determine the optimal combination of fly ball rate driven power and BABIP. Moving along to doubles, we find that Progressive is more favorable here, while once again both parks inflate the hit type. Rosario has been a solid doubles hitter throughout his career, though that rate fell off a cliff last year. A boost here is a nice positive for his extra-base hit prowess. Somehow, and amazingly, Rosario hit a whopping 15 triples during his 2015 debut. Is that for real?! It almost looks like a mistake. He has never hit more than two triples in a season since, so that’s as bizarre a start as there is. Target has been quite the triples park, while Progressive suppresses them. But now, that won’t matter since he isn’t much of a triples hitter anymore. Last of the hit type factors is home runs, where we learn that Progressive is quite the happy place for left-handed sluggers. Target actually reduced lefty home runs, so this represents a nice boost for Rosario’s HR/FB projection. Rosario has posted HR/FB rates just below 16% over the past two seasons, and a mark just above it in 2017, with his 2018 and 2016 mark coming in around 12%. The park switch now gives him a better chance of setting a new career high HR/FB rate. Now we move to the plate discipline factors, strikeouts and walks. The factors are nearly identical at or near neutral, so there’s not much to discuss. Rosario enjoyed a big boost in walk rate this past season, but had generally disdained the base on balls before that. Incredibly, his strikeout rate has improved significantly since his rookie year, almost declining every year in lockstep. He’s now at a point where it’s quite impressive combined with his power. Last are the batted ball type factors. For some of these, there’s no actual good, as that’s very hitter-dependent. Really, more line drives and fewer pop-ups (IFFB) is what a batter wants, so those had the potential to be highlighted. But, there’s no GB or FB park factor that’s better than another, so no highlighting was made there. It is interesting to find that Progressive reduced fly balls. I wonder what the cause of that is. Rosario has posted FB% marks above 40% for three straight seasons now, so I wonder if a decline would actually increase his wOBA, with more hits falling in, and enough so to offset the loss of a couple of homers. We also find a nice positive surprise in IFFB factors, where Progressive has suppressed pop-ups quite significantly. Perhaps the same cause of the lower FB rate is resulting in fewer pop-ups as well. Rosario’s IFFB% has generally been around the league average, but because he hits so many fly balls, his raw pop-up total is high. Fewer pop-ups should lead to a higher BABIP. Overall, this was definitely a positive move from a park switch perspective. At the very least, Rosario’s new home should be more favorable for his HR/FB rate, while the FB and IFFB factors could potential increase his BABIP. Moving into a less productive lineup could offset the park switch, of course, but that’s a discussion for a different day.