Bello threw his slider during a live batting practice session Thursday, Ian Browne of MLB.com reports.
Adding a slider was a point of emphasis for Bello during the winter. "I felt more comfortable with that pitch," Bello said. "I feel like I can throw it in any count. [Thursday] in live BP, I used it and felt really good about it. So it was a good offseason for that pitch." The slider could be a good third pitch to go with a filthy sinker and changeup. The right-hander said he also plans to use a four-seamer outside the zone to elicit chase. Additionally, the 24-year-old worked on his lower half and back during the offseason, hoping not to wear down over the course of the season. Bello hit a wall late in 2023, losing his final three starts, including the final two outings in which he allowed 13 runs over nine innings. That brought his overall record to 12-11 and swelled his ERA from 3.68 to 4.24.