It can be as simple as something clicks in during a game or practice through all the repetition (and it might even be hard to articulate it) Once it starts to work, the muscle memory takes over. As quickly as that comes, it can leave you too, or pitchers make an adjustment that negates the slight change you have made. It is not just a matter of chance. These guys are making adjustments constantly, most are imperceptible to others, even their coaches. Most adjustments are not major adjustments. It is funny that the same people here who will tell others that they cannot judge whether a player is a good hitter or fielder without advanced stats, because of "lying eyes" are trying to put forth a case that they can tell when a streak is random as opposed to something done by the player. Too funny. I guess that their eyes don't lie.