In terms of power feats, Tyrande is extremely weak in BfA and SL. She has done things far beyond them… even in the actual gameplay of Warcraft 3, but especially in novels.
Pre-Night Warrior rituals, she has:
Summoned an army of the Dead
So skilled in hand to hand combat that she could battle a wielder of the Axe of Cenarius while unarmed, only conjuring a divine weapon from Elune’s power.
Could kill waves upon waves of undead which were being backed up by multiple Frostwyrms. As a bit of a 2 for 2 feat, Tyrande’s pure faith and devotion to Elune and the Kaldorei and this moment was completely unbroken even as he fully believed she would die there, because of how raw wc3 Kaldorei were as a warrior culture that didn’t buckle or flinch, and would join their warrior goddess in death… you know, before they did sexist crap to Elune’s writing so they could justify undead nelf souls empowering Sylvannas in SL.
I would argue that it is not because of this. He’s the direct students of gods, who taught p much all other druids until BfA added in Thornspeakers and Raptari. Cenarius chose him because he was one of the few Kaldorei not absorbed into the folly of the Highborne Empire’s culture, and paid homage to the ancient myths and customs. Everyone else laughed at the idea of Cenarius being real, Malfurion believed it.
Narratively, Malfurion’s power is a demonstration of power gained by serving the land itself. He contrasts with the other night elves who ruled his era, such as Azshara, because they really only cared about power in it’s raw and tangible forms. Whereas a Druid, while being able to condense these amazing evolutionary processes, to wield the same spirit and determination that flows through the heart of everything growing, isn’t powerful out of a desire for power itself. It is oneness with the land.
To make a comparison to Fandral, and why Malfurion would be so much stronger than him in terms of his connection to Nature: and in a funny way, this ties into some of the East Asian inspiration in Kaldorei Lore (such as how Buddhism is about imperimence, why Buddha says ‘Everything changes and nothing lasts forever.’) Malfurion had been shutting down Fandral’s idea of Teldrassil, before blizz even retroactively added other dumb world tree like Vordrassil or Shaladrassil or the Great Trees, because he believed it clung too much to the past that they’d just sacrificed for the greater good. Their desire for immortality back was natural, but he was there preaching that they would perhaps be even stronger if they tried to be mortal again. That they’d find a closer connection to nature than ever before, by living within it’s cycles while still being it’s guardians, rather than protecting it yet being outside the natural ravages of aging, diseases, etc.
What gave Malfurion such a strong initial connection to nature in the Ancient World was partly being the direct student of Cenarius himself, but rejecting a lot of the unnatural aspects of the ancient culture of the Kaldorei. This grew when the rest of his culture began to follow him and returned to following Cenarius (which is why he’s essentially like the Kaldorei equivalent of Luke Skywalker) and readily embracing the change that his people had heroically made at their own expense to fulfill the duty that the Aspects had put onto them years ago.
Narratively he has also been shown to be stronger when pushed to defend what he loves, something you can tie back to what Goldrinn as a spirit, embodied within nature itself.
“the animal instinct that kicks in when wild things smell food or feel their children are in jeopardy.”
In the way that protecting the things you love and cherish is a part of our innate nature, it kind of fortifies his bond with the land. Because a lot of Druidism is about how these aspects embodied by the Wild Gods, Strength, Tenacity, Endurance, etc, are there in every person. Even IRL, these are products of our being. We are, each and every one of us, the offspring of an unbroken line that has endured at least 5 great mass extinctions in the history of our world. At the core of every living thing is strength and persistence, every person and creature, and in a way this ties us to nature, even when we IRL often feel so disconnected from the wild and the natural.
And at the very least, this power has been there since he was first introduced to us as “The wisest and most powerful Druid” back in wc3. The power boost Sylvannas had, definitely was not set up before 8.2.5. Both of which still got in better than Tyrande, cause the writers make her look extremely weak compared to her abilities in the earlier lore, but also make her look like a weaker person by making her faith and devotion to the Kaldorei look flimsier. Tyrande was to the Kaldorei IN UNIVERSE, what Sylvannas is to undead fans, the ‘shining light’ that epitomized the best, most devoted, and fiercest part of their people.