I gave RW another go just now, and came to a quick conclusion:

In an effort to make matches go faster, SE, please understand you didn't do this. Matches ran long because people were still pretty new, they often didn't take advantage of opportunities or momentum when gained (often in lieu of overprioritizing the generator), OR people were just riding out the clock if in the lead.

What you've done now however is create a situation where the team with an exposed core is now forced into desperate defense, such to the point that any possible ability to try and make a counterpush is hardly possible. Weakened cannons can't handle the combination of advancing mechs and escorted mammets due to less range and lowered damage, and players are forced to defend if only to maintain what's already generally a losing condition.

Simply put: Where match length was largely a fault of players not exercising good strategy (I've seen matches end QUITE fast when one team makes the right moves and coordinates, and this is even without premade teams), the adjustments now provide near-insurmountable advantage to the aggressor team. If your team is forced into core defense, then so long as you actively defend, you'll never be able to do much else where before there was a bit of breathing room and opportunity, even against a strong enemy push.

That said, I'm sorry but I just can't, and won't support Rival Wings as it currently is. And while I won't actively discourage anyone from Rival Wings, I certainly will not encourage participation, and please know that it is in direct correlation to the erroneous changes you made in 4.18.