raising the arm pushing the tackler's high is an interesting one. players are certainly taught to raise their arms out of or over the tackler's arms so they can get a handball out. you'll also see many players jump up just before being tackled raising their arms. so the raising of arms to effect a handball when tackled is certainly coached. whether this also increasing the chance of a tackle slipping high is a byproduct or or a deliberate ploy is problematic. certainly some players (and repeatedly) do it to draw the free and not to free the arms to handball. there are other 'techniques' employed to draw a free too.