TURNING POINTS:

First, you have probably noticed there is a condition even better than Best. It's the jumping happy face, but it's only temporary.

Now, there are 3 momentum switching situations - Turning Point, Attack Point, and Defense Point. From my experience, this is when they happen and what will happen:

TURNING POINT - When the game is close and late, and a lead is about to change hands. If the attacking team scores successfully, all hitters will immediately become Jumping Happy Face in that inning. If the pitching team is able to get 3 outs without the opponent scoring, then the pitching team's hitters will all become Jumping Happy Face in the next half inning.

ATTACK POINT - This seems to happen only when a team is losing by a few runs. If that team scores successfully, all the hitters will receive Jumping Happy Face immediately in that inning. This is the game's way of giving this team a chance of coming back. However, if the pitching team shuts them down, the pitching team will not receive any bonus, since they are winning by a lot already.

DEFENSE POINT - Just like attack point, this only happens for losing teams. you are down by a few runs already and your opponent is threatening to score more (maybe a couple of guys in RISP). If you shut them down successfully, your team's hitters will receive jumping happy face in the next half inning, giving u some momentum and a chance to come back. However, if the opponent scores they do not become jumping happy face in that inning.

As you may notice, only hitters can become jumping happy faces, not pitchers. If you don't like this gimmick then you can turn it off in the Match Settings under "Turning Point". Personally though I leave it on just for fun.

You can see in this in-game screen that the green arrow (top right) signifies that there's currently a Turning Point active.