I do my best to shot call on Primal for the Immortal Flames as well, so I'm just going to share from my experience.
In general, as long as you can take the reigns and direct people where to go, most people will tend to listen. However, be wary with how often you spam macros to get people's attention. As someone in the chat itself pointed out, if you spam it far too often, people will get annoyed and refuse to listen to you. However, people still do want leadership, so doing something is better than nothing.
As far as your Summoner gameplay - I play summoner as well, and some of my advice is that you death flares should be timed a bit better. Sometimes you time them too quickly and they won't finish off a kill, merely get them down low enough for someone else to finish them off.
Otherwise not too bad. Clearly you're doing a great job - you won by several hundred point margins.
Here's a video I recorded incase you want to see it from another perspective. Close match, but we did still win and I did 10/0:
https://www.youtube.com/watch?v=M9sv00ZnqGs