I did a more in-depth look at stats recently, I confirmed that levels and stars are virtually identical.
Every hero gains a set amount of Offensive/Defensive modifiers (stat multipliers) every time they level.
When you add a star, you simply increase the amount of modifiers that each level provides.
So a level 6* Halloway gets 4.5 normal offense modifier per level, so at level 80 he has x360 offense modifier. Meanwhile a 7* Halloway gets 5.7 normal offense modifier per level, so at level ~63 he has x360 offense modifier. So a level 80 6* Halloway has almost identical stats and power as a level 63 7*.
So no problem right? Wrong. The issue is skill levels. When you add a star, your skills are also upgraded for “free”, but when you add a level, you have to pay up to 43 power (at plat) to level each of your skills. So back to our 2 Halloways, if they are plat then (assuming the level 63 Halloway has maxed his skills), then level 80 6* Halloway must either:
- Leave his skills at 63, his core stats and power still match the 7* but not only are his skills weaker, but matchmaking is likely to penalize him for having underleveled skills.
- Raise his skills to level 80. Now his core stats and skills match the 7*, but the 6* Halloway now has 731 more power than his “identical” 7* level 63 version.
At level 85, gold heroes will pay 1,260 power for skills that are equal in power to level 40 with roughly +3 stars. In other words, the level 40 team is basically getting 6,000 power worth of stats compared with a level 85 opponent of equal power whose team has had to dump that 6,000+ power into an extra 45 levels of skills. There’s also a lot of gamesmanship with people leaving skills low, matchmaking usually punishes them but why keep that aspect of matchmaking around where legit newbies might get crushed in matchmaking because they haven’t bothered to level useless skills.
Of course skills should still have an influence on power, but it seems to be far more preferable if we just took a flat 400/600/800/1000 power increase when we unlock the skill.
TL;DR: Leveling your heroes gives them a “skill power tax” that adding stars does not… as we add more levels every few months the problem only gets worse. Add a flat power increase when skills are unlocked, end of story.