I think this game would benefit greatly if the Battle Log contained some sort of box score summary. How much total mana each player produced, how much loyalty, how many times each card was cast, how much total damage each damage source did, etc.. Whenever I’ve manually tabulated this, I almost always come out ahead of the opponent playing the same walker.
For example, my average Koth generated 14.46 mana per inning played, while the opposing Koth players averaged 12.53 mana per inning. So, my mana production averaged 15% higher for the same walker. But when my Gideon I faced a Koth, Koth averaged more than twice as much mana per inning, because that’s what Koth does. Solution? Play Koth over Gideon I if winning is your goal.
The only time cascading really gets out of hand is when the opponent has something like: Part the Waterveil, Ulvenwald Hydra, something that draws cards when spells are cast (Prism Array, Rashmi, Baral), and a bunch of spells which turn 15/20/30 gems green.
Some planeswalkers also cascade more than others because their first ability can change gems to their color or destroy gems that aren’t their color (Nissa I, Nissa II, and especially Koth. Chandra I used to cascade a lot when her 1st ability cost 3. Now it costs 6 and you rarely even see her played.)
I haven’t seen any evidence that the opponent cascades more than I do, on average, other than those decks which are designed to do nothing but cascade (which I would play if I didn’t lack certain key cards). Overall, I averaged 13.1 mana per inning tabulated, while the opponent averaged 8.8 per inning they played. This means I averaged about 48% more mana per inning played (largely due to Planeswalker selection).
Of 288 full innings tabulated (that is innings where my opponent and I both had a turn at bat), I produced 65 mana one time (Nissa II), 40 or more mana 5 times (Nissa II, Chandra II, Nahiri, Koth, Sorin), 20 or more 38 times, 10 or more 128 times.
My opponent got 69 mana 1 time (Koth), 40 or more mana 4 times (Koth x3, Nahiri), 20 or more 19 times (50% as many as me), 10 or more 82 times.
The Battle Log doesn’t state how much mana is generated from cards like Drownyard Temple, Behold the Beyond or from abilities like Dovin Baan’s 1st ability, but I do believe that, statistically, I am cascading at least as much as my opponent, if I am playing the same walker and using the same deck.