Do you consider Wagner part russian forces as such? I think they had some success because they are not. They are entrepreneurs not bound by sovjet style bureaucracy, which gives them room to maneuver and the units freedom to act and adapt. And, they had thousends of expendable lifes to waste that didnt have an impact on russian public opinion. Russia really only made fighting progress where Wagner went to die.
So far Ukraine have had the advantage being defending against mostly russian regular troops doing pointless head on grinding attacks. I sure hope the ukrainian armed forces made some reforms and progressed into something else than a sovjet army like russias. Or else this ukrainian offensive is just going to mirror the russian failed attempt.
I think it's quite clear Wagner operate outside Russian traditional C&C control.
The reason why they weren't performed as badly is not because of this tho, it's rather those people who serve Wagner have been in all kind of situation from Syria to Mali and know what they were doing in war, on the contrary, Russian military is all but a domestic force, I can't even remember when the last Russian Peacekeeping Mission is since KFOR that can get them some limited deployment experience, mostly Russian Force are a domestic force, it would be like asking the US Army National Guard to deploy to a high intensity warzone without giving them some start up experience, that is always going to be a fail.
Another point is Wagner is a commercial entity, and they are generally better armed individually than that of a Russian soldier, I remember talking to some of my colleague where I work and both of us looking at some picture of dead Russian soldier at the beginning of this war, they are very under equipped. they lack the things we considered standard individual equipment in the west, things like Tactical Com, Optics, NVG, Modular Plate Carrier, even cheap stuff like elbow pad or knee pad were not standard across the entire organisation. You can predict how your army do by looking at how much the cost for the equipment they carry, and I estimated back in March 2022, their individual equipment is no more than $2000 with the rifle. Wagner, on the other hand, have probably better equipment to start with, as they were constantly in deployment from middle east and africa, that's why they performed better.
The problem is, now there aren't not much different, the overall mood of Russian troop are going down, and Wagner have lost most of their experienced personnel, and have seen regular people and prisoner joining their rank, that edge is probably all but gone now. And they are probably no better than the Russian Armed Forces. Maybe the only thing different is there is something you can look for if you are a Wagner Prisoner. But that wouldn't change the equation much.