I'm aware now that Zen Sphere will do the most damage if used on cooldown, I read the post and it was pretty interesting. It's just I have the feeling your spreadsheet does a very flawed approximation of melee damage abilities, for example look here:
https://www.warcraftlogs.com/reports...-done&source=8
I can see here it's better than two jabs and an RSK, but your melee damage estimates seem to be quite lowballed. You'll see that with your stats, two jabs and a RSK come out around 2/3 worth of 3 Zen Sphere casts (assuming one detonate hit). This is fairly consistent in all of your logs with ZS, but your spreadsheet seems to output that one ZS would do double the damage of two jabs/rsk.
I'm not sure how you're calculating them, but with my own program and your raid buffed stats I'm getting the following:
Average Jab : 5033
Average RSK : 36473
Average ZS (1 target) : 25851
Note this isn't taking into account 20/26% from RSK, but the values would seem to be proportionally closer to your actual average RSK which is hovering around 90k or so.