One problem that Destruction Warlock had was a number of talent rows with very obvious "single-target" vs. "AoE" talent picks. This has clear downsides--a requirement to swap talents often (and as a corollary, a feeling of being significantly crippled when not using the ideal talent loadout for a given situation). Clearly, it's a DPS loss single-target to say you can no longer have both Eradication and Reverse Entropy, and a DPS loss in some AoE situations to say you can no longer have both Cataclysm and Fire and Brimstone. But making that swap, and then making sure throughout PTR that Destruction DPS remains reasonably consistent with live, will leave the spec more well-rounded and not as pigeonholed by talent choices in a given situation. PTR already has buffs to Doomguard and Imp damage that help with numbers in all situations, as well as buffs to various talents to help futher improve flexibility.