"Throwing at Giratina-O - Help needed"

#PokemonGO: Any advice/eplanation as to what is happening?Problem occurs - when/after the boss drifts up and down.Problem - Some of my throws receive a phantom "boost" and shoot up the screen faster than usual... I will throw with the exact same finger action but one throw will get an excellent and the next throw will pretty much hit the top of the boss. I’m not sure exactly what causes the boost to kick in.(It's really making Giratina-O catching tough for me as when the boss is in the low position and the "boost" is active I cannot make a throw low enough to hit an excellent/small great no matter how tiny I try to make my throw. Then there will be a moment when the "boost" goes off and I just basically drop a ball onto the floor when trying to do a short throw.)My Phone - Samsung S7, android.My throwing technique - Set the circle, hands off the screen, wait for boss to attack, then make my throw.PS - I know some people I have mentioned this too have said this doesn't happen to them and they suggest I must be throwing differently, but there are also a number of regular raiders who are experiencing the same thing as I am, and have experienced this with other bosses that drift up and down.Can anyone offer an explanation as to what causes this? Or how to avoid it happening? via /r/TheSilphRoad http://bit.ly/2WRF1Bs