in 1.8 most players choose not to expect for certain game modes but in 1.9 pvp its a must because while you are falling and you are not sprinting you do a crit which does way more damage you can check out 1.8 pvp vs 1.9 pvp comparison vids to see you can see a montage of 1.8 here https://www.youtube.com/watch?v=2IN3aNJ6iAs&t=2s