As A Support Tank, Your Job is to Protect Your Laner
NOT go roam mid for 15 minutes then come back wondering why the enemy bot laners have 5 kills on your adc. Your job as a tank is to protect your team, specifically your squishies. That includes ADC and mid mages. Again. That means to PROTECT YOUR LANERS.
If you are blitz, a pull of a carry to our team if theyre fed is a bad idea. A pull of their fed carry away from your carry is much better. That is always an option. You can peel. Regardless of what your position is.
If you are thresh/any other tank, don't be afraid to innitiate. You can easily get inbetween the damage and your carry. You can also prevent most projectiles from hitting your carry. If your carry dies, and you arent trying to keep them from dying, it is your fault.
Before you say anything, I am a support main. I just got out of my final ranked placement (i normally request support then fill) and happened to get ADC. My blitz did absolutely nothing all game to defend me or anything. He landed maybe 2 pulls in lane and didnt try many other times.
That is all.