Single-A Clearwater placed McFarlane on its 7-day injured list Saturday with an unspecified injury.
The 22-year-old right-hander has piled up 68 strikeouts over 49.1 innings, but his struggles with walks (16.3 BB%) have played a large role in him carrying a bloated 5.84 ERA and 1.71 WHIP through 16 starts. It's unclear if his injury is significant enough to cut short his second professional season.