To add on to this, consider more direct comparisons between 2020-2021 and 2017-2019 HOTM.
One of the most obvious comparisons is Clarissa vs Gravemaker. Yes, Clarissa has better stats across the board. This is what we would expect if HOTM were getting stronger each year. But Clarissa also has considerably lower poison damage (224 to Gravemaker’s 298). This more than offsets the slight stat boost.
Or perhaps consider the decline of the mana controllers. 2017 brough Hel, who at average speed completely shut down the mana gain for 3 heroes. She also had 315% damage to the target with minor damage to nearby enemies and extra damage to holy enemies. 2020 gave us Zocc at the same speed. However, where Hel stops mana gain for 3, Zocc only provides mindless attack to 1. He even does less damage at only 300% to a single target. And 2021 gives us Balbar whose sleep can be broken by a single off color tile. And he still only controls 1 at the same speed as Hel with less damage overall.
Or let’s look at snipers. 2018 brought us Alasie with 462% damage and an undispellable -24% mana generation to 3 at fast speed. 2019 gave us Kingston with 445% damage to 1 and an increasing attack drop starting at -31% to 3. 2020 gave us no snipers and the closest we have in 2021 are Uraeus with 485% damage to one and conditional sand damage, or Russell with 350% damage to 1 with burn damage to 3, and a guaranteed hit. Not only are the extras (sand and burn vs mana slow and attack drop) less impactful for the newer HOTM, but both are average speed. If HOTM were truly getting stronger every year, both Uraeus and Russell would be fast.
Perhaps we should consider the premier healers of each year. 2017 gave us Alberich with 153 HP/turn for 4 turns, a 33% revive chance, and direct mana gain. 2018 brought Delilah who was among the first average speed healers with 33% healing and minions with an additional 13% HP. 2019 gave us Kunchen with a 42% heal and a defense drop. Even 2020 was decent with Raffaele providing the largest overall heal in the game. Then 2021 dropped off with Alexandrine and her base 18% heal that is dependent on tiles (ignoring the precedent set by Ratatoskr).
These examples do not show HOTM getting stronger over time. In fact, in most cases, the only improvements are in their base stats. But if the special skills continue to grow weaker than those of their older counterparts, the net result is that the HOTM are in fact getting weaker over time.
Meanwhile, event heroes continue to get stronger and stronger, both in terms of special skills and base stats. Therefore, if the more accessible HOTM are getting weaker, while the less accessible event heroes are getting stronger, the only way to offset this is to give them some sort of buff that makes them more competitive.
A 5-15% crit chance buff simply will not cut it. They need something much more substantial. As is, I doubt even the 20-30% crit chance will be enough.
