Of the many differences between the two largest DFS sites, none is larger than the late swap versus no late swap feature. FanDuel does not offer late swap, meaning once the first pitch is released in the first game on the slate, all roster positions lock for the night. On the other hand, DraftKings offers a late swap feature, meaning a roster position does not lock until start time of that player’s game.

There are some good reasons that, especially in the summer, a DFS gamer would prefer to lock in his action for the night at first pitch and not have to worry about making adjustments later. Typically, the first games on a slate lock in at 7:00pm Eastern, with more games locking in at various times between 7:00 and 10:30pm.

On a busy slate, you will typically find one or two late starts. When facing your opponents on DraftKings, you see only their players rostered once their game starts. If you’re in a head-to-head game, knowing who your opponent has remaining would be quite powerful, obviously, and would be used in different ways based on situation, aka game theory.

Taking an extreme example, let’s say all pre-10:00pm games have completed and both you and your opponent have one starting pitcher left to go; Arizona at San Diego. Doing a quick calculation of your opponent’s salary used so far, you see that he has $11,000 of his $50,000 total budget remaining, same as yourself. In the pitching matchup of Greinke versus Shields, it doesn’t take a genius to figure out that you have both rostered Greinke.

Now what do you do? Well, it depends upon what the score of your game is. If we are trailing at all, even just a fraction of a point, we should switch to Shields every time because even if Greinke throws a perfect game, we cannot win with him on our roster.

Our opponent, holding a lead, is never switching to an inferior starter when he is out front. On the other hand, if we are the ones leading, we stand pat for two reasons. First, as mentioned, we are running out the superior player and projected higher scorer, while making our opponent beat us with a clear second choice. In addition, this is a late game and there is always the chance that our opponent is busy or sleeping and doesn’t swap out, in which case our game is over the second it locks.

When it comes to game theory in a GPP baseball tournament, you have to weigh your own comfort level into the equation. What this means is that to play optimal game theory, you have to be willing to sometimes sacrifice cash positions in order to play the lesser option if it’s the only way you can possibly take it down.

Let’s use the previous example of Greinke versus Shields in the final game remaining, Arizona versus San Diego, and we are currently in 12th place in a large GPP tourney within a few points of the leader and there are five gamers in the top 11 with a remaining pitcher. Getting out the trusted calculator, we quickly compute that all five are indeed rostering Greinke.

We now know with absolute certainty that keeping him on our roster guarantees that we cannot ship the GPP and that our ceiling is sixth place. We don’t play GPPs to finish outside the top five, however, so we decide to flip Shields in before lock and go after the big payoff. We are sacrificing a very likely sixth place finish in a huge GPP field in order to go for the win, and if Shields implodes, not only will we not win, but we will start seeing many gamers who previously trailed us come shooting past, knocking us down the pay scale in their wake.

This is where you need to know yourself and know whether the mental grind of the downside is something you can be comfortable with. I think, being the clear +EV play, that you should be at peace with the decision, but everybody is different.

You might tell yourself, “Everyone else chasing the top guy is going to switch to Shields, so leaving Greinke in can potentially net me second place.” This is just not true, however. While the swap will very likely happen when playing head-to-head against a trailing opponent, in a large GPP, you will have a combination of less experienced gamers chasing the big prize pool for their small investment, ones that are completely unwilling to swap out a player they’ve put aside 22% of their salary cap for and ones that will not give game theory a second thought.

There are big edges to gain on your competition long after the first pitch of a DFS slate is thrown; sharp players who employ some game theory to their in progress card will be, for all intents and purposes, playing with an extra hole card in their hand. It may get rivered on one night, but over the long-term this advantage will pay off handsomely.