Now I dont know how the reward system will work, but if it is similar to the realm rank system in DAOC it could help to promote less zerging, more defending.
If the system rewards players MAINLY for killing other players and the amount of damage they did.
You will see alot of players who want to raise their rank so they will start to stray away from the zerg so they can get more credit for player kills. you might actually start to see alot of roamng 5man groups picking off people and looking for other small groups.
another thing people dont think of from DAOC was taking keeps JUST to defend and make points form enemy attackers, SO you might see groups taking towers and actually staying there to defend.
They reward system would also need not have a cap that could be obtained in a few months, refer to the DAOC realm rank system that get progressively harder where rewards eventually get few and far inbetween, so you keep building your character for years.
Now if the system follows the karma, big reward for taking undefended keeps and avoiding player kills, this system will not fix anything
Not going to hold my breath but if done correctly the reward system could make WvW alot better