ICYMI, The GIST launched our official MLB partnership this week with a striking data point: It’s the most-attended sports league by women fans. Women are feeling increasingly welcomed by America’s pastime — partially because stadiums across MLB are more inclusive than ever, thanks to additional accommodations and partnerships with companies like Aunt Flow. This week, we spoke with Aunt Flow founder and CEO Claire Coder about the company’s partnership with MLB teams and how the league is considering women fans and their families with improved infrastructure, including access to free period care. About damn time.

A season that spans 162 games from March to September provides plenty of opportunity for pondering. The introduction of the Automated Ball-Strike Challenge System (ABS, more on that below) is undoubtedly the biggest shakeup of the season, but first, here are the other major storylines we’re following before first pitch.

This year’s campaign features an intriguing plot twist: The introduction of the Automated Ball-Strike (ABS) challenge system, which will allow players — specifically the batter, the pitcher, and the catcher — to challenge an umpire’s ball or strike call. From how it works to the unexpected fallout , here’s everything you need to know.