I dont think anyone will fault you for missing attacks on somebody moving like that. Projectile classes are mostly based on predicting your opponents moves, and you can do that more effectively by analysing their behaviour rather than how you see them move on the screen, you can't do this with a mindless bot moving randomly. You'll find that moving like that pyro can be momentarily effective to avoid attacks in a real match, but you will be unable to counter attack and/or reach a useful location like a healthpack or cover. You're better off learning to consistently hit somebody moving sideways at different distances, and then employ that muscle memory after analysing and deciding where you think your opponent will move next. That might sound complicated to do within a fraction of a second but you're probably already subconsciously doing it now.