One of the first things Trevor Bauer said he wanted to do when he joined the Reds was to figure out Luis Castillo’s changeup. Who wouldn’t? It’s one of the most dominant pitches in the game, one Castillo has thrown nearly one-third of the time this season, second-most in the big leagues.



Once he was with the Reds, Bauer asked assistant pitching coach Caleb Cotham to get him some of the team’s video from high-speed cameras that record bullpens. There, he sat and watched Castillo throw his changeup.



Two days after Bauer’s first start with the Reds, he got to watch Castillo up close. Castillo struck out 13 batters in that game against the Angels and allowed just three hits over seven innings. Castillo threw 119 pitches that day; 51 were changeups and the Angels swung and missed on 18 of them.



“I need that pitch,” Bauer recalled thinking. “It reignited (the) need to figure out that pitch.”



Bauer...