Why rehabbing Pirates first baseman Spencer Horwitz is a great fit for PNC Park

The Pittsburgh Pirates acquired Spencer Horwitz this past offseason from the Toronto Blue Jays to serve as their primary first baseman. Although he is opening the year on the IL, he should be back in action before the end of April. Horwitz had a great 2024 rookie campaign with the Toronto Blue Jays, batting .265/.357/.433 with a .344 wOBA and 127 wRC+ across 381 plate appearances. He only struck out 18.9% of the time with an impressive 11% walk rate. He ranked in the top five among rookies with at least 300 plate appearances in OBP (first), OPS (fourth), wOBA (third), and wRC+ (third).

One criticism many had of Horwitz is that he is not a big power hitter, but most metrics that we use to measure home run power actually saw him as a slightly above-average batter in this department. He had a .168 ISO (league average was .156), an 8% barrel percentage (51st percentile), and a 3.2% home run rate (3% was the league average last season). However, there is another, much larger reason why his home run power will work for the Pirates; he is a great fit for PNC Park.

New Pirates addition Spencer Horwitz is a perfect fit for new home at PNC Park

According to Baseball Savant, PNC Park is one of the best parks for left-handed hitters. Their park factor of 104 is the fourth-highest in baseball, behind only the Colorado Rockies’ Coors Field, the Boston Red Sox’s Fenway Park, and the Cincinnati Reds’ Great American Ballpark (100 is league average and is on a similar scale to stats like wRC+, OPS+, or ERA+). It is also more favorable to home runs for left-handed batters, with a 102-park factor.

Meanwhile, the Blue Jays' Rogers Centre suppresses left-handed batters and is more favorable to pitchers, with a park factor of only 98. That only ranked 22nd among all 30 ballparks. It was also far less home run friendly for lefty batters with a 95-park factor, just the 19th-highest in baseball across the last three seasons. The only sort of hit that Rogers Centre helps facilitate for left-handed hitters is a double; at 114, Toronto's park factor comes in fourth-highest in that department.

However, the difference between PNC Park and Rogers Centre for left-handed hitters when it comes to doubles is minuscule. PNC ranks right behind Rogers Centre at No. 5 at 113, making it a very similar environment in that regard. Triples are the only type of hit that Rogers Centre greatly favors over PNC, with a 93 park factor compared to 68. But Horwitz has hit more than one triple in a season just once since getting drafted, that being last year at Triple-A when he had a pair of three-baggers. Doesn't seem very relevant.

Horwitz’s home/away splits also support the fact Rogers Centre isn’t very kind to left-handed batters. The infielder batted .229/.330/.382 with a .313 wOBA and 106 wRC+ in 186 plate appearances at home. That is still above-average production, but most of his value came from his 11.9% walk rate and 16.8% K% at home. His ISO of .153 was roughly league average, and he did not collect many hits, either. His sOPS+, which is similar to OPS+ but compares a batter’s OPS in a split to the rest of the league’s split OPS (in this case, compairing Horwitz's home OPS to the rest of the league's home OPS), put him at just a 99.

But on the road, Horwitz looked like a completely different batter. In 196 plate appearances, he turned in an outstanding .298/.383/.480 triple-slash, .374 wOBA, and 147 wRC+ player. He saw a slight uptick in K% to 19.9%, as well as a small decrease in walk rate to 10.2% on the road, but both were still above average. Notably, Horwitz hit for much more power, with eight home runs and a .181 isolated slugging percentage. His sOPS+ was 146.

Horwitz’s type of game will play a lot better in PNC Park than it did at Rogers Centre. He is in a park that is more favorable to home runs and singles for left-handers, and nearly as favorable for doubles. Horwitz’s splits at home and away last year show that Rogers Centre could have been suppressing his abilities because, on the road, he hit for a lot more power.