Okay, I haven’t been able to find the forum post tracing Garrosh’s progression, but here’s a link to Alex Afrasiabi explaining how they originally planned for Garrosh to be redeemed and become a “strong Hellscream leader”:
And here’s part 2, explaining what happened in Stonetalon:
Out of curiosity, why were you glad that Stonetalon was an anomaly?