Who can quickly explain this "stack" stuff. People make it sound like if you stack a QB and WR from the same team, you save money? You get no discount on your salary cap when you do this, correct? Sorry, noob here.
When you stack a QB and WR (or TE) from the same team, you're not getting a discount on your salary cap. But you are increasing your chances of having a very high or very low score from that combo instead of a medium score. This makes sense in tournaments, because a very low score is generally no worse than a medium score: you're out of the money either way.
Let's say you've got Kelvin Benjamin at WR, and now you're choosing between Cam Newton or Matt Ryan at QB. If you select Ryan, the QB-WR combination could be great-great, medium-medium, horrible-horrible, great-horrible, horrible-great, medium-great, and so on. All combinations are perfectly likely because the QB's performance and the WR's performance are uncorrelated.
But if you select Newton, now certain options that lead to an overall medium score (like horrible-great) are much less likely. The odds of great-great and horrible-horrible are increased, while the odds of great-horrible and horrible-great are decreased, and the overall effect is to make the combined score more volatile. Compared to the Ryan-Benjamin combo, the Newton-Benjamin combo is more likely to be very high or very low, and less likely to be medium.
That's an advantage in tournaments, where we're really trying to avoid mediocrity.
It's not a huge deal. You can have a great tournament lineup without stacking, and you can have a great cash-game lineup with stacking. But at the margin, as just one among many factors to consider, stacking is generally a point in favor of a tournament lineup.