Tengu vs Eclipse is far from the most egregious example eclipse doesn't even have that much more HP than tengu but it does have much greater speed and energy capacity. 

In general it's like after the grade update all the mechs and weapons have the same power rating they did before the update and the new stuff has had its power rated in relation to other mechs of the legendary grade. Causing what's actually a much greater power imbalance than what you see in the numbers.

Paragon for example has the lowest rating of any mech. The highest rated mech, parasite, has greater than 200% more HP than paragon. And it's got not more than a 34% higher power rating than paragon. How are these this close in power rating?

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Now let's look at weapons. Missile rack 6 vs Storm rack 6. Storm rack 6 has 14% higher power rating than missile rack 6. But does it look just 14% better?

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Keep in mind not shown in this image is storm rack also does 50% additional damage to shields so even if it was the exact same weapon a shield mod can be like 1/3 of a mech's HP so even if storm rack was the exact same weapon with extra shield damage it would be 15% better, but IT IS SO MUCH STRONGER THAN THAT STILL! How are these weapons' power ratings this close? How does this make sense?

It's done this way so you fight against them and want to upgrade to a better mech/weapon... Considering the fastest/easiest way is with money... 

Missile Racks are absolutely useless weapons - high reload time, low possibility that you'll actually hit opponents unless they are stunned or slowed down. Even the damage is not that high, considering how long the reload takes. 

I hate that I have to use this weapon to finish some achievements (Ares or Reedeemer) while these mechs have no slowdown or stun abilities.