The flip side to the Russian loss equation:

In any war, there are mistakes made by either side at the outset that either get corrected over time or lead to a protracted front where casualty-aversion is the name of the game. This is the nature of how both sides grow their "veteranship" over time as they learn what tactics work and which ones will get your whole unit murdered. Mariupol will be a big turning point because once it is taken it will do some big things for Russian field commanders:

It will demonstrate the effectiveness of the "use artillery barrages to inflict casualties while minimizing friendly losses" model that will no doubt be adopted in other urban sieges around the country once it has proven its effectiveness in the south. This is how commanders learn and adapt from the successes of their counterparts.

The other big thing it will do for Russian commanders is open up more logistical resources. With Mariupol leveled and leftover resistance there slim, Chechens and other veteran units that Russia has in Mariupol can be recommitted to taking Odessa or consolidating the eastern Oblasts.

Finally, we need to look at who the Russians can loop in. They're already tapping Syrian and now Libyan troops (Run Marty!), but word on the block is that there is a real chance of Belarus getting pulled into a conflict it is already ankle-deep in. If Belarus commits its military to the Russian cause, that's like several new northern fronts opening up just north of Kyiv. If this occurs, the map looks a lot different. Same thing if the Russians continue to employ the "more artillery, fewer casualties" model across the north. The Russian military is already offering Mariupol the same thing it had previously offered cities like Idlib & Grozny: "Capitulate and cease all resistance now or see the city you are defending reduced to ruble."

The Ukrainians can resist these tactics, but absent intervention by US/UK/France (NATO won't do it), expect to see that Russian casualty rate to go down while the civilian casualty rates goes way up.