As always, I really enjoy your data-driven posts. The breakpoint for Sloane especially is really cool to see!
A section on the power of upgrades would be really cool! Like "here is the win rate of Sloane with Level 1-3 arbalest vs. Level 4 (when it gets an extra attack). It'd hard to disentangle the contribution of the arbalest explicitly, since if they have a leveled sloane and arbalest, they probably have other leveled cards, so there might just be insufficient data to look at it.
Thanks for the feedback. We could probably do a section on upgrades later on. So far, I dont think there is enough data with leveled monsters for this right now to be very accurate. After general sale tho, I think this will be very interesting to try out, and I will definitely look into it.