What if i would have bought the Ultra model instead, would that be better for sports?
Only if you have a 4K TV. It's possible that TSN is the source of the issues.
Does that phone device that i'm casting from make a difference? I'm using a MOTO E4.
Not with a Chromecast in direct streaming (from the source) mode. For apps that mirror the screen, like Miracast and a few others, it might make a difference.