I say that any other snafu's on Grell's part were a writer coming into his own and combined bad decisions by editorial.
You do realize that Mike Grell has been a comic book professional since he started on Superboy and the Legion of Superheroes in 1973, right? I'd say he's more than come into his own by now.
Even if you mean he was coming into his own as an Iron Man writer, he still had plenty of background as a writer of various genre characters to go by. I like Mike Grell's work on John Sable, Warlord, Green Arrow, and Shaman's Tears. Outside of a couple of stories in his IM run, I couldn't connect with his Iron Man at all.