What are you doing wrong? Worrying about those two flyers, I'd say ;-)! Sounds like really good shooting to me, those last two were probably a combination of things, among them being pellet, gun, and shooter fatigue. I find that 5 10 shot groups are more fatiguing than 10 5 shot groups. Over exercising my short attention span, I guess. Just keep doing what you're doing, I wouldn't change a thing. Later.
Dave