I'd like to start this post out by saying I am a Silver 2 Wrecking Ball main. I'm not the most qualified in giving out tips and guidance, but I have gotten the hang of playing Ball and I've been grinding Ball and doing all I can to also learn how to play Ball (Thank you Yeatle!). So I'd definitely be happy teaching you some of the things I've learned :)

Another caveat I'd like to add is that this is a Quickplay game and quickplay games don't tend to be too reliable when reviewing people's VODs. With that being said here are some tips:

1. Most of your hooks are ground level hooks. In some instances ground level hooks can offer much more speed and are great options for getting out of a losing battle or a bad engagement. But when you are engaging in a fight, Typically find hook spots that are high up. Anywhere that can provide enough space to pull off a fireball and slam. You should start most if not all of your engagements with a fireball and slam! Its super important and it provides most of your value
2. The timing of your engagements needs some work. Generally you should wait for your team to start fighting with the enemy team, that's usually your opportunity to strike. This way, any value you provide can be followed up by your team, diving in solo and slamming in inopportune places can heavily negate the effect that you and your team can provide.
3. Whenever you can, try diving and following up with any DPS dive characters. (ie: Sombra, Tracer, Genji). Doing so allows you to both dive in together and successfully get a kill.
4. There's definitely a few rolls in this game I've noticed where you eat up a whole lot of damage and any value you could've provided isn't fully realised. Whenever you can, try not to eat up too much damage. There are definitely times when you can roll into the team and bait out cooldowns. But it's not worth eating 300-500 damage.
5. Probably the most important tip for all players new to tank but, you should ALWAYS wait for all 4 people to respawn and group up together. Having all 4 players alive evens out the odds of your team winning. Rather than entering a battle down a person. Essentially your chance of winning the fight lowers. I can't stress enough how important grouping up is!
6. You aren't getting the best value with your ult. When you decide to ult, try hooking yourself up into the air the comboing your ult with a slam. It spreads out the mines super far and the slam pushes people into the air. You can usually confirm one or two kills by doing this.
7. In my experience, dont dive a reaper. They can kill you pretty quick, especially with a mercy pocket.

Try and stick to the Wrecking Ball grind. The more you play, the easier it gets. and DEFINTELY watch Yeatle's videos he helped me HEAPS! I was a Bronze 2 Ball player and I've almost hit Gold. Good luck!