Prior to the nerf I was already seeing fewer Telly tanks in upper diamond.
Post nerf it seems that there are fewer than that. The Titan Mafia data will show us top 100 results.
The nerf was very effective. Small tweaks yes, but it is at the margins that we win or lose. So, less damage (she is an AoE so less but x5, 796 (Telly - Damage) to enemy team to 450), less healing (16 per round per hero) and weaker minion shield (from approx 200hp to 140hp) with around 60hp less. It adds up.
Telly is now easier to beat, much easier. She isn’t useless but she is no longer fearsome (her HoT is only two turns as is her mana reduction).
My biggest objection to the nerf is that she no longer seems good on offense. I have taken her on some raids and she really fluffs her lines.
The heal is now too low to really help the team. C-Rigard is faster and heals more (609hp/3 turns vs. 274hp/2 turns) not to mention he cleanses and buffs the attack (the cleanse is often as good as a heal now with so many DoTs in the game).
The nerf effectively reduced Telly’s healing by ~95hp/per hero each time she fires.
C-Rigard heals for as much as 609hp, Telly up to 414hp when including the minion.
Therefore, if wanting a healer for your attacking team, Telly is no longer enough. Bringing two healers leaves you too passive.
Telly would be interesting on offense if the mana slow and healing were bumped up to three turns (keeping the heal per turn the same).
The nerf was extremely effective. She remains a decent tank but no longer shines in any other role.