Personally I would include movement and positioning in DM. Split game skill into 3 categories of deathmatch, knowledge, and teamplay.
Deathmatch is the "execution". Knowledge is "knowing what to do". Teamplay is "Knowing what your teammates do and supporting each other".
All three are used in every play, like imagine a small fight occurs on granary second, 2v2 flank attempts a backcap as rest of combo push into mid 4v2.
Teamplay is the flank on both teams knowing what each will do, and the relative combos also knowing what their flanks are doing. "Do we trade uber as the mid defense? Are the flank winning the 2v2? Are the combo coming back or trusting their flank?"
Knowledge is just knowing the answers to these questions and reacting accordingly. "Yes we trade because we are getting the backcap because they are winning the fight" or "Combo is coming back, we must set up on mid and buy time behind them for spawners since our flank will die soon".
Deathmatch is how these are executed. Winning your fights, hitting your shots and being in the correct position to do these things. Standing on high ground and shooting down making shots easier to hit is good deathmatch. Players who have bad aim but stand in good spots will have better DM than someone who has good aim but stands in bad spots.
This is pretty overly simplified since all three feed into each other seemlessly but the question kinda wants an objective answer and likely all three are equally important for any individual player.