First base was a massive issue the Pittsburgh Pirates needed to fix this offseason. As stated earlier, Connor Joe will likely see some games at first base, but they also acquired what is likely to be the platoon as well. Part of that platoon is Carlos Santana, who only batted .202/.316/.376 with a .308 wOBA, and 102 wRC+ last year. It wasn't a great year for the first baseman, but there were still a handful of positives.
2022 marked the 11th season in a row Santana walked at least 13% of the time and struck out less than 20% of the time. He's mastered plate discipline throughout his long career. Santana still mashed left-handed pitching to the tune of a .265/.387/.402 line, .354 wOBA, and 134 wRC+. Santana was in the 75th percentile of exit velocity (90.7 MPH) and 76th percentile of hard-hit rate (44.9%). Of all Baseball Savant statistics, he was below average in just two: sprint speed (16th percentile) and arm strength (21st percentile). Plus, as a first baseman, speed and arm strength are the least of their concerns. He was also in the 59th+ percentile of all expected statistics.
Santana had a poor season but has arguably the best player comparisons of any player we'll look at today. The first player is 2022 Christian Walker, who batted .242/.327/.477 with a 122 wRC+. That's far from the best player.
The second player is Anthony Rizzo, coming in with an even better .224/.338/.480 line and 132 wRC+. 2015 Matt Holliday is the next player who hit .279/.394/.401 with a 125 wRC+. Now here's where things get interesting. The fourth player Baseball Savant compares Santana to is 2016 Josh Donaldson, the year he batted .284/.404/.549 with a 157 wRC+ and finished 4th in AL MVP voting. Finally, you have Yandy Diaz from 2022, coming in with a .296/.401/.423 line, and 146 wRC+.
If you average out all those numbers, that is a .265/.372/.466 batter with a 136 wRC+. It's not as if Santana has never posted similar numbers. In 2016-2017, Santana batted .259/.365/.477. But those are some very optimistic numbers, and it's unreasonable to expect Santana to replicate them.
However, do keep in mind that Santana was one of the most shifted on batters in 2022 when he faced a right-handed pitcher (batted left-handed). 98.1% of his plate appearances as an left-handed batter were with a type of shift on. While that isn't to say that Santana is all of a sudden going to put up prime Josh Donaldson-like numbers, it's not unreasonable to expect him to post better numbers next season.