Oh, It's pretty far-fetched. You do realize that there's an entire layer of fat (in Dale's case) and abdominal muscle in between the skin on the stomach and your intestinal track? Your stomach isnt covered by a pudding skin for cripe's sake. Unless that zombie held his finger to a grinder in the barn and sharpened it like a scalpel he's not gutting a conscious, struggling human that easily.
yet "zombie overdrive" wasnt working when he was stuck in a mud hole for 15 minutes as Carl threw rocks at him from 3 feet away?
Again, my only gripe, is if you're gonna make the zombies strong, killing machines, then make them that all the time. Don't weaken them to the point they get felled by swamp mud in one scene, and then hours later have the same exact one doing solo takedowns on cattle and ripping people's limbs off.