I bought a brisket (ginormous) and cut it down the middle. I did a rub on one for a day and brined one for a day. Smoked at the same temps, same day, same rack, same final temp, same everything, however one has a nice smoke ring, is awesome tender and exactly what I love in a brisket. the other (rub) ZERO smoke ring, less flavor, and not nearly as tender. Now I realized a marinade similar to a brine will change the texture, moistness, etc, but why would the smoke ring be so significant in difference?