That's what I thought about being a lead designer but then I look at both the incomplete Iron Heroes and Heroes of Shadow, the latter being a late era 4E book that came out at a time when all the other designers seemed to be getting better at 4E.
And that segues into your points about Keep on the Shadowfell and Pyramid of Shadow (not Thunderspire): I don't think he ever really grokked 4E in a way Chris Perkins or Rich Baker did.
I must make a correction in two places Vor-Rukoth was not Mike Mearls but Greg Bilsland though it does suffer from the "almost there" problem usually seen in Mearls' 4e work, which I think was the point [MENTION=22362]MoutonRustique[/MENTION] was trying to make.
And you are correct it was Pyramid of Shadows, not Thunderspire. I just could not remember which was which.
To me Rich Baker, more than anyone in the design team, really clicked on how to expand and bend the system - maybe since Book of 9 Swords is one of his. Dark Sun brought the inspiration of Themes. Which I think are a brilliant broadening of the base leveling mechanics without impacting power level. Gamma World brought the idea of a completely compatible setting that could sit side by side within the same design space. He also wrote Red Hand of Doom, which to this day is my second favorite adventure.
Anyway, for me he's the guy who killed 4E. (And I say that without bad blood or emotion. I have all the material I will ever need!

)
I would not view it so harshly but I understand the sentiment. I feel the same about material. I'm having a great time with the campaigns I'm playing and running and I have more than enough material to last me several lifetimes. I've always converted adventures and I'm having a great time doing that with 4e.
He ensured it had a bad beginning with Paizo's favourite adventure Keep on the Shadowfell - the adventure that launched a thousand Pathfinder campaigns
I had to laugh at that one.
... and then presided over Essentials, the fake revised edition that didn't even bother to have a PHB.
I don't see Essentials in such a dark light. I liked the fact that Essentials really showcased the robustness of the 4e underpinnings. You could build character classes that did not have to use the AEDU framework, and they could stay well balanced, and even interesting. They could play side by side with AEDU classes and still be lots of fun.
My son plays in our games and he prefers the slayer to the fighter, but he's added things like artificer (multiclass) to the things he likes. I think Essentials was great at broadening the spectrum of the classes and providing very simple classes for those that wanted them.
I also liked that they added the capacity of existing classes to broaden even further. For example the ranger could get some cool primal powers. I've never liked spell casting rangers as a base, but with this I was able to kind of have flexibility without multiclassing.
So I don't think Essentials was a total stinker, there were parts I really liked.
I don't think he will screw the pooch with 5E, though: clearly more AD&D-like editions are near and dear to him... and the strategy of outsourcing adventures means he won't be writing any!
I've liked some of the stuff he wrote for 4e, like I said Return to the Moathouse was fun, but I think it might have been fun because of the nostalgia factor more than because it was 4e. I also liked the basics of Essentials and I liked Hammerfast because it did have that "almost there" vibe that I could use. So not everything he did was crap in my mind.
It was an interesting turn because I think the stuff for 3e like Iron Heroes had a lot of good ideas. I just did not see anything similar from him with 4e.