I don't know why you're pointing out about Sully and Randle giving you two undersized power forwards. You're focusing too much on Kelly's height, and not so much on his softness and lack of wingspan.
That may be because his alleged "softness" is fully imaginary.
Yeah, it really isn't. He has a tough time guarding strong and athletic bigs. Not to the extent that some like to assign to him, but it is an issue for him. He's not Bargnani soft, and he's actually positions himself fairly well (improving throughout the year as it was), but there's a lack of strength there that doesn't favor him. And when you add how many people here like to consider him as a Center, particularly as it regards in comparisons with Sully, it becomes even more of an issue.