THIS IS TL;DR SO IF YOU DON'T WANT TO READ SKIP TO THE END FOR MY BALANCE SUGGESTIONS

I've split most of my playing time between USN BB and CL and noticed some irritating trends in tier progression.  Mostly how sometimes you will grind upwards and be rewarded, and sometimes you will be punished for your efforts.  I decided to map out some of the primary ship stats of the CL line and see how the tier progression really looks like, where the problems lie, and how they can be fixed.

First off, the stats themselves.  These were taken from the research tree, or checking the CL directly for defense level.

Notes: 

• T11 defense levels are assumed, and I clocked the Omaha reload times by hand, so it is a rough estimate.  If someone can give me the Cleveland's defense level that would be great.
• Gray cells denote values with no upgrade options in the research tree
• Dark orange is for ships whose gun count in the research tree is higher than what you can actually fire at once.  Omahas have 10 guns, but only 7 can be fired in a broadside, and Atlanta has 16 total, but only 14 can be fired per broadside.  As such I excluded those extra guns as they do not contribute to DPS.
• Teal fields denote mandatory uprgades to get to the next tier.
• Differentials refer to the percent change in that value from the last tier, without having upgraded (except for the teal values of course)  This is important to see what the base change in stats is when you get the next ship.
• I have excluded secondary gun batteries because they aren't a prime contributor to DPS and seem to scale linearly.  Also laziness.  I may add them in later.

You can check the stat sheet with the original excel file if you wish: http://www.filedropper.com/nfusnclprogression

This analysis assumes that only mandatory upgrades have been purchased.  If you analyze the differentials with full upgrade stats, things start to look rather bad for the entire progression, but that is beyond the scope of this post.  Here I aim to just go over the basic errors in the tier progression.

THE DPS:

Immediately you notice two big things:
1) The DPS jump from the T3/4 Omahas to the T5 Juneau is HUGE.
2) There is a DPS drop in T9/10.  The T9 drop is roughly 10%, which was a nerf instituted back in March since the Brooklyn was raping everyone.  The further drop in DPS to T10 is worrying however, which I will explain later.

Some of you might wonder why the T6 Atlanta DPS falls off, but the Atlanta has 6 torps (3 per side) and capable secondaries which more than make up for the slight main gun DPS drop.

DURABILITY POINTS:

The progression is  quite smooth and gets a nice even boost at high tiers. However, you once again see that the T2/4 Omaha is wholly inferior to the T5 Juneau.

SPEED:

The base speed progression is perfect, showing a nice linear increase.  However you'll immediately notice the absurdly large (and mandatory) T3 speed upgrade.  The rest of the chart seems strange, but it makes far mtoe sense when you look at the differentials, so I'll leave discussion for that section.

DEFENSE LEVELS:

A smooth baseline with two upgrade spikes at the T5 Juneau and the T9 Brooklyn.  The Juneau's upgrade is optional, but the Brooklyn's is mandatory to progress to T10.  This is problem for the T10.

DIFFERENTIALS:

The big one.  This ties everything together and gives you a percentage increase/decrease in stats at each tier compared to the last.  So for example if you upgrade from T5 to T6 you'll see a 2-4% rise in dps, dp, and speed, with no change in defense.  If you upgrade from T6 to T7, you will get a -2-4% drop in DPS, and speed, no change in def lvl, and a boost to DP. 
For clarity i've labelled the defense level differentials since their values are too small to be meaningful as percentages when compared to the rest of the stats.

We see a few interesting things here:

1. The T4 to T5 gap is astounding.  Looking at the graphs above we see that the issue isn't so much the Juneau being overpowered, as it is the T3/4 Omahas being horrible in every way except T3's speed.
2. The T9 Brooklyn sees an alarming drop in DPS, but has a defense level boost, and when we look at the stats we see that upgrading defense level to 7 is mandatory.  This makes the Brooklyn exceptionally strong because it has great survivability which offsets the small DPS drop (which can be eliminated with a cheap gun upgrade anyways).
3. But it comes at a cost to the T10, which has both a DPS drop from the base Brook, and a huge defense level deficit of 3.  There is a mandatory speed upgrade to progress to T11, but +3 speed doesn't do anything against a BB, CA or CL that knows what its doing. Basically, the T10 is inferior to the T9.
4. Because the T10 DPS is so low the T11 Cleveland is a huge step up in firepower.

What is my interpretation of this?  Well there are two things that I assume about the way the progression should be set up for player satisfaction that I shoud mention:

Players should NEVER be given a downgrade unless it comes with a counterbalance (such as Atlanta getting lower DPS but torpedoes, or Brook gettign lower DPS but great defense).  If you make someone work their butt off only to play something worse you punish effort and deincentivize further grinding.
Ships should not be excessively superior to their predecessors, as this exacerbates MM imbalances.  A T4 vs T5 CL should be a win for the 5 based on stats, not a statistical blowout.  When stats are so unbalanced it reduces the role that skill plays in a battle.  And as such, when MM sets up ships theoretically one tier apart, the actual difference can be far greater and lead to a crushing defeat and frustration.

SO ->

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MY BALANCE SUGGESTIONS:
T3- Remove speed upgrade as mandatory.  Make DP upgrade madatory and make the DP boost to 37000 to offset speed loss.
T4- Give a speed upgrade to 38.4, and make it madatory for progression. Buff gun damage to ~1100 (for DPS of 1283).  Give 2x3 torpedoes, firing on alternate sides like the Atlanta (Yes, the Omaha had torps!).  Boost DP slightly to 35000. This should make the Omaha at least a bit more competitive and bridge the gap to T5.

T5- Nerf gun damage to 773, with DPS drop to 2279. Set upgrade gun damage value to 825 (slightly higher than what it is now) for DPS of 2585.

T6-8 - Leave as is, they are well balanced.

T9- Reduce defense upgrade to 6 to slightly nerf the Brook.  It is way too tanky and gives an unfair advantage for being only T9.  Not that I can complain since i regularly raped with it, but fair is fair.
T10- Decrease base gun reload to 4.79, with upgrade to 4.55.  This will boost DPS to base of 2434 and upgraded to 2802, putting it below T8 dmg, but closer to T11 and making it a match for the Brook.  If you ask,
"Why not buff defense level?" it's so that the playstyle is different from the Brook.

Thoughts and input appreciated.