After raising some questions on the feeding capabilities of mando and nix, I decided to run some tests. Below are the results.
(URL in case image is low quality on TMA:
http://i.imgur.com/qzmyJfb.png)
Feeding capability was measured based on DPS.
As you can see, a base mando is better than 2 base reapers, and a level 4 mando is better than 3 max level reapers. It takes a little more to beat vikings (levels 4 and 5).
The BC autoattack is trash compared to base mando, although yamato deals 400 damage with 50 AoE, for 2000 burst AoE damage. If we assume this happens about once per minute, the real BC damage output is about 7.5k per minute. In that same minute, a base mando deals about 6.4k damage, and a level 1 mando deals about 7.7k damage.
In short, 1 mando level outfeeds a BC.
Unsieged tanks will basically always outfeed mando.
The nix story is even more ridiculous, beating all max level elites listed right out of the box.
The HK numbers are deceptive - don't forget that they kill themselves as they attack and are hard countered by mando, nix, and spec. I didn't post DT numbers, which as you would expect are insane (base DT has 100 dmg per swipe, with splash), but DT's are also hard countered by mando, nix, and spec, as well as scanning and obs.
The point is, mando and nix never have to stop attacking, while DT and HK do.
The elites I listed here are pretty much the main autoattack elites that people use in that manner (ghost and sentry, for example, were excluded).
Let's also not forget mando line-snipe which kills anywhere from 5-15 units per shot, and the nix lift ability that can AoE lift half of the opponent's army. Spec also has AoE stun.
Conclusion: Mando and nix are OP denial, and a team with both can deny anything. Additionally, they feed WAY too well, given their roles as OP denial.
Suggestion: Pretty obvious, nerf their DPS, and nerf it hard. They shouldn't be able to outfeed anything. :C