OVR versus match rating
The decision
OVR is an input to the simulation. Match rating summarises contributions in rounds already played. They describe different things and use different scales.
How it works
Arena Rating combines kills, deaths, assists, damage, KAST and opening contribution. Around 1.00 represents balanced performance. A strong player can still have a poor map.
Practical interpretation
Consider sample size. A brief excellent map is not the same as a sustained season. Use OVR and roles for drafting, then rating and detailed stats for reviewing play. These are not predictions of real professional matches.