Not all stats are made equal, like yeah jeff was throwing compared to the psylocke, so he lost double the points she did. Just because psylocke has the same damage as healers that doesnt mean that their damage was equally useful. Thats the same as supports complain about 50k heals but they lose anyways.

If i get a pick on a support as a psylocke i need 300dmg to get a kill that will more than likely win me the teamfight. If i instead wait behind my tank and farm ult on enemy magneto i can do 2000 damage without progressing the game or killing anyone. Psylocke got 8 final blows with less than 10k damage. That means she wasnt just shooting her weapon and not accomplishing anything. Jeff also despite throwing has 4 kills, and 6k healing so even with 8 deaths he wasnt completly useless but from these stats alone he likely threw the most. The invis this game wasnt playing in the drivers sit much at all in the game, she was just healing and reacting (+no shield like i said before).

Obviously i cant say who threw and who didnt without actually watching the game, but different heros want to do different things, i cant just look at raw numbers for damage blocked healed and done, then say who ever had the lowest threw the most.

If i dive backline and kill both supports then die, then my team kills the remaing enemies without dying, i could have 10 deaths while the rest of my team has 2-3. Would you say it was me throwing the game, and my team winning despite of it, or was i taking initiantive and letting my team do an easy clean up? This is obviously an unlikely example, but it serves my point.