I've noticed something - the Astros pinch-hitters are doing a lot of pinching, and not a lot of hitting.
In fact, let's look at this. In 36 games in a pinch-hitting role the Astros three standard pinch-hitters are...
Erstad: 4x15, 1 triple, 6K:2BB, 2RBI
Michaels: 2x15, 1 double, 0RBI, 6K:2BB
Smith: 0x13, 1RBI, 4K:0BB
Total: 6x43 (.140), 16K:4BB