Not looking for a mentor, but needing a bit help

Dunno if this is quite the right place to post this so please move it if it's not.

So, my 'problem' is that I keep getting these bizarre winning streaks followed by long streaks of really unenjoyable and uneven matches that more often than not end up in losses.
Couple nights ago had the last match which I already feared was going to be the last good game from the streak of 20-30 games. Like clockwork I started to get really obscure/bad matches again.

At first it was the mandatory stompfest loss where the enemy team might as well have been 7k since their 4 stack was just phenomenal from picks to coordination whereas the 4 stack I had gotten picked fun heroes with little to no gameplan.
Should be no surprise that my team gave up (a bit prematurely imo, but all the same in the end) at 30 min mark as the enemy team just chained stuns with almost bot like precision, nuked with perfect timing, blinked in just close enough to cast a spell, but still be outside out the other hero's casting range.

..and like before, the downspiral has begun again.
Whether it's horrible team morale from get go or just terrible picks (on my team, some times myself included) I just can't figure out what I should do differently because at this point (after ~10 or so uphill/downhill trends of 20-50 games, the previous one lasted almost 2 months) the fault has to be in me and i'm also getting pretty tired of it.
Alternative option would be that Valve hates my guts but, I wouldn't be able to do anything about it so that's not an option either even if it was possible.

My dotabuff is: http://www.dotabuff.com/players/49756387, incase that would give some idea.

Anyway, any tips/help on what I should do so I wouldn't be stuck in this eternal loop of long high highs and even longer low lows with no middle ground at almost any point (though in retrospect, the high highs might actually be middle ground since I don't enjoy stompy games in any form) would be very much appreciated.

I can't use the link to get to your Dotabuff for whatever reason, but it sounds like you might be on the cusp of switching skill brackets? A little extra effort in your games, or maybe some mmr grinding with a hero you're very good at, might get you into a more comfortable and enjoyable position.

Could be dead wrong though.

Safecyn, remove the comma at the end

http://www.dotabuff.com/players/49756387

Dat Masaaki, always looking out for me. Thanks! Now let's see...

Ahh. Interesting. You used to pick Dark Seer almost exclusively, but now you're branching out and picking other heroes. Which is great! But it seems like in your efforts to diversify, your skill bracket went down. Understandable if you're unfamiliar with how other heroes work.

Honestly, I wouldn't worry about it too much. I know losing streaks suck, and yours do seem a bit longer than usual, but your winning streaks do seem to outweigh your loss streaks. I'd relax and just tell yourself you're still learning.

Alternatively, you could try just taking a break when you feel that loss streak coming on. Mentality is a big part of performance, and resigning yourself to a loss streak is a surefire way to go on tilt and start making poor decisions. If you want an example of that, just check my dotabuff here: http://www.dotabuff.com/players/66065800

Bask in the glory that is me doing my Ember Spirit challenge.

Thanks for the reply.

I'd still (almost) exclusively pick dark seer but, sadly after 6.85a-c (one of the best if not the best dark seer patches I've played) he was (imo) nerfed a little too much.
Since he isn't that great in late game (for aghs to pay off later way too much has to go right).
So that basically leaves the early, mid and early late game but, the few nerfs to him really took down his utility...ness/synergy in random pubs quite a bunch.

The skill bracket drop happened after I took a break and tbh I wasn't too bummed about it since towards the times before the break, a whole lot of games were just excruciatingly unpleasant. So, I was even a bit happy about it since I'd get a chance to enjoy Dota again.

I usually start deviating from my 'regular' heroes when I don't do ok/well with them and now that I think about it, that might be part of the problem if not THE problem. I get highish due to being pretty familiar and comfy with my trusty heroes (starting from the lowest point due to counter picking heroes I'm not good with), but when I hit a wall I deviate from them and face a long "wind down" due to playing with heroes that I'm nowhere even close to being on the same level as e.g. with dark seer.

well, that mystery is half solved now, thanks :D

Follow up to my previous conclusion.
It turns out my idea of the whole situation being caused by me almost exclusively picking dark seer/performing tenfold with him and more poorly with other heroes wasn't the issue in the end.
After posting (over 3 weeks ago), I stopped picking dark seer and other heroes I was good with in hopes I'd start to get less of the painful win/loss streaks and excruciating flat out terrible games one after another where the enemy team outperforms mine on every conceivable level.

Long story short(er), the past 3 weeks I've had the worst games during my 3 years of playing Dota.
Even more disheartening is that the quality of games I've been getting has been dropping rapidly, not even a glimmer of light.
Not only am I consistently getting matched against increasingly more difficult opponents, but I'm literally being matched with people who have 30-40% win rate or just started the game/have level 1-5 accounts (not the whole team, just enough to matter).

I'm completely out of ideas of what to do. Counter picking doesn't work (has adverse long term effects), randoming doesn't work (adverse effects from not knowing the heroes), playing a handful of heroes I'm good with doesn't work (severely adverse 'medium term' effects), exclusively picking Dark Seer doesn't work (inability to have enough impact late/late late game in pubs).
Only thing I can think of to fix this is to quit Dota, again.

Edit: Played a handful of games this weekend (randomed, 'luckily' got heroes I'm quite comfy with) and the loss streak continues. The skill bracket is probably getting extremely low now since most games end due to some pub stomp strategy (usually these disappear the higher you get).
Even though I see them coming I can only be at so many places at once (usually more than 1 pubstomp 'strategy' going on at once so even if you stop one the other can just do whatever he/she wants) and if I get support then leaving my carry to feed is even worse than not stopping the impending menace in the horizon since then there is absolutely 0 chances of winning and I get reported.

Edit2: (a month later) What worked wonders was reducing my playing amounts to couple times a week. Instead of the depressingly bad games I was getting before I got nice games although quite a bit skewed against the enemy team. As long as I kept playing as rarely as I did, I kept getting easy or good games.
Then I thought I'd give a go with playing a bit more again and the terrible games reappeared almost instantaneously and now out of the last ~20 matches have lost 16 due to what could be described as "1k vs 5k".
The differences in the teams have been insane again, the teamwork and expertise of the enemy team almost without exception has been far far superior in comparison to that of mine. From great picks to efficient farming to chainstunning like unfair bots, with 5 random players, not even 4 stacks all the time.
Maybe some day I'll figure out what matchmaking wants from me, until then it's less doto again :/