I’ll level with you, readers: I’ve been taking it easy for the last few weeks, enjoying the end of the year and starting to get recharged for 2024. Not much baseball is going on, spring training is still quite a bit away, and we haven’t even had many exciting signings or trades to break the doldrums. It’s only natural, given that kind of backdrop, to let your mind wander.

One of the things I found myself wondering about was how Tyler O’Neill would like playing in Fenway Park. On the one hand, it seems like a match made in heaven; O’Neill is a righty hitter who puts the ball in the air, and Fenway is a perfect park for hitters who can pepper the monster out in left field. On the other hand, O’Neill’s power is absolutely gargantuan; if you hit the ball 400 feet, how far away the left field wall is doesn’t matter much. Heck, the wall might turn some smashed homers into doubles or even singles; it’s just so dang tall.

Statcast data bears that worry out. In 2023, O’Neill only hit nine homers. That’s bad enough, but here’s the kicker: per Baseball Savant, he would have only hit six homers if he played the entire season in Fenway. That’s actually tied for the stadium that would have allowed the fewest homers – Camden Yards and its new left-field cutout is the other laggard. Some of that is because O’Neill doesn’t hit dead pull shots all that often, and some of it is because no matter how crushed this baseball was, it didn’t get high enough off the ground.

Of course, it won’t always be that way. In 2022, O’Neill hit 14 home runs – but Savant estimates that he would have hit 16 in Fenway. In his career, he’s hit 78 homers, and Savant estimates that he would have hit 76 if he’d played every single game in Boston. This kind of analysis can only get us so far, however; it’s very sensitive to precise parameters, and it’s hardly predictive. It also doesn’t truly account for the benefit righties get from the park; plenty of O’Neill’s outs would turn into base hits, and even the lost homers would almost certainly become doubles.

I wanted a more specific representation of what Fenway changes for righties, so I went to the data. I took every pulled batted ball hit 90 mph or harder by righty batters at a variety of launch angles in the 2020-2023 seasons – I skipped everything before then because the composition of the ball was changing so much in those years that I’m afraid of messing up the sample. I bucketed them to see which combinations of speed and angle led to the most damage, both in wOBA and slugging:

Those numbers don’t make a lot of sense without context, so here’s the same statistics, except instead of Fenway, for every stadium in baseball from 2020-2023:

And crucially, the difference between league average and Fenway. Here, I highlighted the combinations where Fenway boosted results by at least 150 points of wOBA or 300 points of slugging:

This is saying what we’re all thinking: if you hit the ball hard enough, Fenway doesn’t help much. If you hit the ball low, Fenway doesn’t help much. If you hit it fairly hard and fairly high, you’re looking at a parade of doubles and homers instead of lazy outs.

O’Neill doesn’t hit as many of those balls as you’d think. In his career, he’s hit 15 more Fenway-friendly batted balls than your average right-handed hitter would have based on his number of balls in play, but after you add in all his non-contact events – he either strikes out or walks fairly often – it’s a negligible amount. Relative to your average right-handed hitter, O’Neill isn’t getting much of a Fenway boost; it’s on the order of four extra batted balls a year hit where the park hands out extra-base hits. On the flip side, he also hits the ball hard and low more often than your average hitter; call that three batted balls a year. And these estimates are for if O’Neill played every game at Fenway. I don’t think he’ll be a huge beneficiary of the park, in other words.

That could have been where my analysis left off, except that the Sox turned around and traded for Vaughn Grissom. Now this is the kind of guy who seems like a good fit for Fenway, I told myself. He doesn’t strike out very frequently, which means more balls in play. He has average power, which means fewer screamers that Fenway either does nothing for (no-doubt high homers are still gone) or hurts (a missile off the wall). When he puts the ball in the air, he pulls it fairly often.

I didn’t repeat the exact exercise that I did for O’Neill, because Grissom just doesn’t have enough major league data. I can say this, though: Even though he hits a lot of grounders, he both pulls the ball softly in the air more frequently than your average righty. He also rips low, hard-hit line drives less frequently despite his contact skills. In other words, he has the general shape of a successful Fenway hitter.

That’s not to say the Grissom is a perfect fit. He hits more grounders than you’d like for a player who should be taking advantage of a unique stadium. But that’s fixable. Grissom has never played in Fenway before, so it never made much sense for him to develop a swing perfectly tailored for the park. He has tremendous bat control, which suggests to me that he has more ability than your average player to change his batted ball mix.

Does that mean that Grissom will immediately turn into Dustin Pedroia? Not at all. This is a small edge, a speculative bonus more than a carrying tool. But every little bit helps, particularly for a player like Grissom who’s right on the edge of major league viability depending on how his bat pans out.

For now, that’s the end of my Red Sox investigation. Are they targeting righties whose batted ball mix makes them a particularly good fit for the stadium? Probably not – only one of the two hitters they acquired fits the bill. But did they consider Grissom’s particular set of skills when trading for him? That seems more likely to me; not that the Braves had a particularly enticing set of prospects available in trade, but Grissom has a lot going for him in the context of Boston’s organizational needs and the stadium boost is a nice bonus.

One final aside: while researching O’Neill’s batted ball mix, I decided to figure out which player would be the most Fenway-optimized hitter in baseball. To no one’s surprise, that’d be Isaac Paredes. He makes a living on those lofted pulled fly balls that are decently struck. Per 600-PA season, he hits nearly three times as many balls that Fenway boosts as your average righty. What a hilariously maxed-out archetype of a player. What a delight.

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