Kyle is referring to a fairly specific kind of failure.
When the WiiU launched, the writing was kind of on the wall, but many people refused to see it. It was only after WiiU's second Christmas that the system truly imploded, and plenty of people put together post-launch mortems trying to figure out what went wrong. One thing that was mentioned frequently was that the GamePad essentially doubled the cost of the console, and yet nobody seemed to have any good ideas for how to make compelling games with it (besides off-TV play, which was a convenient luxury). Nintendo just tossed the GamePad out into third party waters and said "Find a good use for it!" but nobody did, largely because Nintendo's own first party wasn't able to make good use of the GamePad (because they never asked for it, it only came into being because Nintendo felt they needed a gimmick in order to succeed, and this particular idea was all the hardware department was able to come up with). The N64 had Mario 64. The Wii had Wii Sports. A new gimmick needs a great game that shows the world (developers and customers alike) what that gimmick can do, and WiiU didn't have that.
Satoru Iwata clearly heard these reports (or Nintendo came up with their own studies which said the same thing), so he said that rather than cut the GamePad loose with a firmware update and make it optional (which was an idea a number of people were tossing around), he tasked Miyamoto to prove that the GamePad was a good idea, worthy of it's inflated cost and worthy of being the primary control method on WiiU. Miyamoto soon after said that he had three games which would do just that, Starfox Zero, Project Guard, and Project Giant Robot.
Some people like Starfox Zero's GamePad implementation, but plenty of other people think that it's horrible and that it's a perfect example of what's wrong with the GamePad. That's the specific failure that Kyle's pointing out, that Miyamoto failed in his mission to prove in hindsight with these three games that the WiiU was a good idea.