An effect similar to drift is observable at tennis, golf, base-ball and cricket; but this effect is explainable by the inequality of pressure due to a vortex of air carried along by the rotating ball, and the deviation is in the opposite direction of the drift observed in artillery practice, so artillerists are still awaiting theory and crucial experiment.
If your bruise worsens, begins to swell, does not fade or begin to fade within a week, occurs for no clear reason or occurs frequently for no explainable reason, you are advised to seek medical attention.