Sean Manaea Heads North to San Francisco

On Friday, the Giants signed left-hander Sean Manaea to a two-year, $25 million contract. Luckily for Manaea, he didn’t have to travel too far to find his new home, as he’ll remain in California. Incredibly, he has now played for three teams, all of which call California home. Coming off a mightily disappointing season that saw him post a career worst 4.96 ERA, will the park switch help fuel a rebound in 2023? Let’s consult the park factors to find out.

Wow, these might be the most interesting pair of park factors yet! In fact, from first glance, they are quite baffling. It’s also not obvious yet whether the switch in home park is a positive, negative, or neutral for Manaea, so we’ll just have to dive into each individual factor to get a better idea.

Starting with the non-home run hit type factors, we find that Oracle slightly increases singles, while Petco suppressed them a bit less than slightly. Singles factors is the biggest driver of BABIP, so all else equal, the park switch means Manaea’s BABIP projection should rise marginally. Though the sample is small with just one year at Petco, Manaea posted a massively lower BABIP at home versus away, at .252 versus .326. Clearly, you can’t credit his home park for the entirety of that gap, though he’s also posted a significantly better home BABIP over his career as well. Of course, he called Oakland home for the majority of his career, and that park is known to suppress BABIP due to its large foul territory.

For his career, he has posted a .290 BABIP, which is probably slightly better than the league average during that time period. His BABIP marks have really been all over the map though, reaching as high as .318 twice, but also finishing at just .247 during a season following one of the .318 seasons. So it’s anyone’s guess where his BABIP might fall in any particular year, but he’s unlikely going to get any help from his new ballpark.

Moving onto doubles factors, we find the exact same marks as we did for singles. Obviously, doubles aren’t as frequent as singles are, but this is just another difference that should increase his BABIP forecast. Finally, we find a big gap in triples rate, where Oracle increases their frequency, while Petco suppresses them. Given the scarcity of triples, I don’t think the difference here should matter much.

Home run factors are next to compare, and unsurprisingly, we find that Oracle holds a nice advantage here. I believe this factor used to be even lower before changes were made to the outfield dimensions before the 2020 season, but since the changes were relatively minor, the park is still tough on home runs. Petco also suppressed home runs, but not by anywhere near the degree Oracle did. Just like his BABIP, Manaea was far better at keeping his fly balls in the yard at home this season than in away parks, posting a 12.5% HR/FB rate there, versus a 17.3% mark away. That’s not that difference than the gap between his career marks, except both are a bit lower than his 2022. For his career, he has posted a 13.1% HR/FB rate, which is a surprise given that he’s always played in home run suppressing home parks. He has never lucked into a single digit HR/FB rate. So the move to Oracle is badly needed, as he could really benefit from one of the more pitcher friendly home run parks. This is especially true if he maintains close to the career high FB% he posted this year.

Let’s move to strikeout and walk factors now. The strikeout factors are nearly identical and shouldn’t have much, if any, impact on his projection. Interestingly, Manaea posted a far higher strikeout rate in away parks this season. While he has also posted a higher strikeout rate in away parks over his entire career, the gap is much smaller. Still, that’s probably a split you don’t see very often! The walk rate factors are more differentiated, with Oracle slightly suppressing them, while Petco inflated them. Not only did Manaea post a much higher away strikeout rate this season, he also posted a lower walk rate. Makes you wonder how he could have possibly posted a 6.16 ERA in away parks, but just a 3.62 ERA at home! His career walk rate split is nearly even. While Manaea’s splits are bizarre, the park switch should slightly reduce his walk rate projection.

Let’s now get to the meaningful batted ball type factors, line drives and infield fly balls (pop-ups). The LD factors are close, and Manaea has posted a career mark around the league average. The IFFB factors are further apart, with Oracle slightly inflating them, while Petco suppressed them. Manaea hasn’t been great at generating pop-ups throughout his career, as he owns a below league average career mark. Any help here would be much appreciated, and work to try offsetting the less pitcher friendly hit type factors.

Finally, we get to the summary metrics, FIP and Basic. It’s quite odd to see Petco at a neutral FIP factor, but quite pitcher friendly Basic factor, while Oracle owns a quite pitcher friendly FIP factor, but only a marginally pitcher friendly Basic factor. I wish I could explain what’s going on here, but sadly, I cannot. It’s clear both parks are pitcher friendly, but hard to say which is more given the discrepancy between the two factors.

What’s better is to summarize how the switch will affect the shape of Manaea’s performance. His BABIP forecast should increase, while his HR/FB and walk rates should be reduced. It’s tough to determine exactly in which direction, if any, his ERA and WHIP would move after those adjustments. So I think the easiest statement to make is that this park switch shouldn’t affect his ratio forecasts much. However, we currently project the Padres for the highest Bat grade on our depth charts, while the Giants sit in the middle of the pack. So you would expect the win potential to be higher with the better Padres offense supporting him. That might knock him down a buck or so in fantasy value.