Board Thread:News and Announcements/@comment-202.156.8.9-20131203051402/@comment-74.75.133.40-20131204042553

They've stated the drop rate on super pieces has remained above 80%, with the other prizes having a significantly lower chance at dropping, so it is still very possible to get the team of evolved supers which you need to compete in events through raiding.

I think the change on raid rewards is very good for the game, especially in the long run. It gives the harder hitting troop members even greater incentive to help out weaker members and rush them through raids, if they can actually get something which is useful to them in the process (boosts, specials)

Furthermore, the incentive for doing the harder rock/wind raids with any sort of regularity just wasn't there before. The troop-wide energy needed is ridiculously higher than a water/grass raid, and the super monster you get is just about equivalent in stats, albeit of a slightly more preferable element. With the new system, they're able to put the most beneficial boosts and rewards on the harder raids, and actually give people a reason to do them more than once for the troop achievement.