Question about SR gaining/loosing

Competitive Discussion
1

Hi

I play mostly solo q.
On my alt account where I usually play tank, I got placed at 2299 and managed to climb to 2536 by earning 45-50 SR per win.
Yesterday I lost 2 games and dropped to 2455. No DC nothing. How can I win so many SR and still loose that many (a bit less though) on a loss?
I still have the plat symbol what does that mean?

Just to be sure. That was my 1st placement on that account. And I don’t say that I belong in plat or something, but the gain/loss of SR is a bit confusing.
(I want to focus on the game not on numbers/wins/losses and play more comp even so that’s not easy ^^" stupid shyness and not existing “thick skin” against toxicity)

Edit: on my winning games I played mostly Hammond and one time Zarya.
On the loosing games I play 1st Hammond then Zarya. The second game I played Baptiste for 4 DDs and a feeding Winston who switched to Rein later.

Help would be appreciated :slightly_smiling_face: