Stats won't say much unfortunately only that you are indeed doing better than average in most games, though I am a sceptic about what I will mention next, but community widely believes that:
You climb when you are playing at a higher MMR consistently, you lose some, you win some, but you will climb if you are of higher elo. No matter how out of meta a champion is, as long as you are good with her, you can make it shine.
I won't comment on stuff like map awareness etc etc because that you can read up about and I suck at it anyway. I like chasing champions and often ignores the boarder picture.
Some tips on Garen
Starting, sometimes I take a 350 sword and a refillable potion, because in comparison to a shield, you have more initiative and compare to a blade, you have more potion to heal + your own passive. I will also take the health bonus conversion as well for the pre-level 2 trading. Garen's armour shred at level 2 from hitting 80% of your spin can caught enemy off guard along with ignite.
l will say you can build more aggressive on Garen to bring him into a more forward carrying position. A yomu with the speed runes from mage tree can add 10-15 ad when you are spinning and more if you have q active. It can make him a very surprising burst for your opponent. Also, i would recommend taking ignite over teleport, because Garen lacks serious ability to catch up once they run away and it is often a good thing to have when you ult don't exactly execute the enemies. That being said, I play him for fun in normals and do exceptionally well with him with some cunning bushing hiding. He is a tough one in ranked, since he is easily countered and his kit is not far reaching, but you can certainly make it work.
For a while, I was an OTP evelynn (pre-mage jungle nerf). It is powerful to being able to play OTP and push your own influence in the game further, but it is up to you to find your champ to play. Though perhaps not with a meta champ for fears of frequent bans.
Finally, good luck and look forward to see your post on your plat promotion!
