Guess you have bad champs, or bad gear /shrug.

Sorry OP but were you not aware that there's a lot of champions who can "Solo" content due to their mechanics? Also that's why you only got 1 Star for the run, you need to bring others and keep them alive for 3 stars. 

That's where the "balance" comes in. Granted the game isn't balanced extremely well, but your example has been tried and found lacking

I don't know if you guys notice but that hero comes from factory and solo all the way up to Rank 8 of Faction wars.

it's not accended, not leveled, no masteries, have crap gear and still solo boss.

while i have whole groups of heroes (level 40) including gear accended etc. and still can't beat a faction boss.

gear might be bad, champs might be bad, level 40/rank 4 is very weak, etc.

in the end you're looking for depth in a shallow stream here. some legendaries are better than others and elva is one who does a reasonable job staying alive (also the small, minuscule detail of being a rank 5 versus rank 4 champ)

Umm you're also not focused on the fact that's a legendary character and your 40s aren't. You're complaining about what exactly? That not all champions are equal in power? If so I don't know why you're playing the game or just realizing this now. Elva is a S Tier Legendary Support, your example is flawed based on that alone. Artak, UDK and Armanz can solo a ton of content with ease. HellHades had a video where he was using Shamael against Queen Stage 20 and didn't realize he wasn't even geared until after the fight. Also, Elva's base speed doesn't change by her level or rank btw. 

Lastly, what you also aren't considering is two things: Faction War bosses have different skillsets and certain champions are better against them AND this is a level 7 Faction War boss. 

I suggest you show us this Roster and the gear they're wearing because all of this is sounding like a gearing or knowledge issue.

Personally I'd say you should be happy you pulled Elva and be glad you can finally progress in Faction Wars further than previously.

Woo hoo 69 more rares and I will have the complete collection across all factions. On a good note though I only have three legos all from daily sign ins. None from shards, no mythical's call my stable home. Is there something broken? I think not. Just an F2P. I guess you get treated better if you pay, pay, pay. Sorry I will never be a whale.