Ruf was diagnosed with a Grade 2 hamstring strain Friday, Kerry Crowley of The San Jose Mercury News reports.
Ruf was placed on the 10-day injured list Thursday, and he underwent an MRI that revealed a strain. The injury has a 3-to-4 week recovery timeline, so the 34-year-old should spend more than the minimum amount of time on the shelf. A better idea of his return timetable could come into focus once Ruf is able to resume baseball activities.