Keller (oblique) has played catch off flat ground as is expected to throw off a mound next week, Jason Mackey of the Pittsburgh Post-Gazette reports.
Keller left early with an oblique issue in just his second start of the year. While it's certainly a positive that he's progressing in the right direction, his next time throwing off a mound will be his first in over three weeks, so he'll presumably need multiple sessions before being returning from the injured list.