Devastate does not appear to be applying deep wounds from what i could see, was using it in raid and whenever i would crit with devastate, no deep wounds dot, im not sure if this is intended or not.
To be fair if this got fixed it would push prot warriors to being better than most of the actual dps specs though lol, already doing 200 dps deep prot in sod, if i went deep arms with deep wounds it would be pretty gross id think.
another thing with devastate, is that it scales off stacks of sunder, so if you have a priest running homunculus for the armor debuff, you are effectively losing 30% extra devastate damage, and with homunculus debuff being better than sunder it causes conflict.