If you hit the brisket or some place like that you'd have heard a lot whack. Briskets don't bleed a lot. I say you plugged him and he's not far away. The only other spots that might yield so much blood on the arrow but none on the ground are the back leg or a hit through the tenderloin. The The back leg would likely leave more blood on the ground than the tenderloin. A front leg shot would also leave blood on the ground... at least for a little ways. If there was a lot of tallow along with the blood I'd believe brisket... but it doesn't sound like it. Tough call when you're there looking at all the evidence sometime. It's really hard over the internet.