No one. End of the article.
It is not a joke. I will explain a little more about why.
It is common to hear that there are people doing Scrum in teams where it turns out that, after the Development Team estimates, the Scrum Master makes an assignment of the tasks. I did it when I started working with Scrum and did not understand what the matter was about.
When I started studying as a Scrum Master it was one of the first things that I changed. It was not easy. There was a lot of reluctance to stop doing it. But, as I always say, I think it was normal. It was an old habit that came before we really started to do Scrum. Management was afraid the teams could not organize the work and agree. The developers did not see it clearly at the beginning either. We started with a team and then we exported it to the others. At the end, of course, no one doubted it and it would be unthinkable to return to that.
The Scrum Guide, when talking about the Development Team, says it clearly in a single paragraph.
They are self-organizing. No one, not even the Scrum Master, tells the Development Team how to turn Product Backlog into Increments of potentially releasable functionality.
The "not even the Scrum Master" is key. The development team is autonomous, no one tells you how to turn the Product Backlog into an increase.
Well, what happens to be more intrusive in someone's work than telling them how to organize it and who will do each thing? The Development Team has all the members that it needs to carry out the development of the product. It depends on a thousand factors, sometimes even on daily conditions, to select who is more suitable or which is the best time to undertake each task.
If you are thinking about the issue of assigning Fronted tickets to Fronted people and Backend tickets to Backend people ... it is not about that either. It is not a matter of "I finish mine and I pass it to you and then I continue with something else and you take care of yourself". The team must work as a team and not just as a group.
"It would be good if today you would look at this with me because tomorrow we can divide this other. I will investigate how to hook what you have done with mine and thus save time for the other. I have touched it and so next time I can start it alone. If we divide this, you can start what you had earlier and we can integrate this part as soon as possible ... "
All this is much more like what should happen within the team and be heard in the Daily Scrum that phrases that would squeak a lot and that before I heard a lot like "I'm with my ticket and then I'll put on the other one I have".
Trying to make a quadrant with tickets for each person believe me that not only goes totally against getting a team to self-manage, but also is to shoot yourself in the foot. You are not going to leave the accounts for hours to square it. It is a system with a zero capacity for modification in the appearance of unforeseen events, steals responsibility to the team about something they have to answer, attaches responsibility to the Scrum Master about something that does not have to answer ... it's crazy.
If you are doing it, stop doing it now. In the next Sprint. It may take some time for the team to get used to it and give them a bit of vertigo, but it is an essential step to self-management.
You can start by being a bit conservative, without a crazy amount of work in the Sprint Backlog and slowly you can help them discover ways of seeing when they are needed and do not see it because they are locked in their task. In the daily, you can see when someone is getting hooked and you can try to establish a dynamic so they can see that it is super healthy for that task to be divided again or learn to share it. And it will even happen that over time some will be firm with helping another because he sees that there is something that if not, they will not get out of the sprint.
It is a matter of taking steps towards taking responsibility. They are the responsible ones that have to face delivering or not the product increment and they will not be responsible for doing it executing a plan that is imposed right? The Sprint Backlog is owned by them, right? Well, the plan to carry it out, too.