FORTUNE -- There's no shortage of embarrassing instances where Apple (aapl) Maps "fell short" -- as Tim Cook's public apology put it -- but on Friday Canadian reader John Garner pointed me to a particularly striking one.
Jason Matheson, a fellow Canadian with a knack for Mac programming, ran a quick Xcode script that compared the iPhone 5's map of Ontario with an official list of the province's cities and towns. Of 2,028 place names, Matheson reports, 400 were correct on Apple's Maps app, 389 were pretty close, 551 were clearly incorrect and 688 weren't on the map at all.
"There's no excuse," Garner writes. "Quality control on Apple Maps had to have been terrible to not get this right. Bluntly, Scott Forstall should be fired over this mess."
Garner is not alone in pointing the finger at Forstall, the senior vice president for iOS software and the Apple executive -- after Cook -- most often described as an heir apparent to Steve Jobs.
In his current Monday Note, Jean-Louis Gassée called the ridicule Apple has suffered these last two weeks "largely self-inflicted." Apple usually under-promises and over-delivers, but according to Gassée Forstall did just the opposite:
"[Forstall's] demo was flawless, 2D and 3D maps, turn-by-turn navigation, spectacular flyovers… but not a word from the stage about the app’s limitations, no self-deprecating wink, no admission that iOS Maps is an infant that needs to learn to crawl before walking, running, and ultimately lapping the frontrunner, Google Maps. Instead, we’re told that Apple’s Maps may be 'the most beautiful, powerful mapping service ever.'"
Forstall did something similar last year when he unveiled Siri -- Apple's voice-activated personal assistant. Although it was labeled "beta" -- computer jargon for "work in progress" -- in Forstall's demo the application seemed not only to understand every question he put to it, but to have a snappy answer. It has not worked so well in the wild, at least not for me.
"Siri has been an embarrassment for Apple," writes Business Insider's Jay Yarow in a piece titled The Apple Maps Disaster Is Really Bad News For Apple's 'CEO-In-Waiting'. "This is his second consecutive high-profile screw up with iOS software."
Forstall came to Apple from NeXT and first rose to power on the strength of OS X Leopard, a project he managed. But it was by creating the original iPhone operating system -- since renamed iOS -- that he achieved his current status. As the manager of the platform that generates more than half of Apple's revenue, Forstall has amassed enormous clout within the company -- and more than his share of enemies.
"If there's a knock on Forstall," wrote Adam Lashinsky in Inside Apple, "it's that he wears his ambition in plainer view than the typical Apple executive. He blatantly accumulated influence in recent years, including, it is whispered, when Jobs was on medical leave."
According to an unflattering profile in Bloomberg Businessweek last year, Forstall has such a fraught relationship with other members of the executive team -- including Jony Ive and Bob Mansfield -- that they avoid meetings with him unless Tim Cook is present. The piece goes on to say:
"Some former associates of Forstall, none of whom would comment on the record for fear of alienating Apple, say he routinely takes credit for collaborative successes [and] deflects blame for mistakes."
That's one way to manage a team. In fact, it was often said that it was Steve Jobs' way. But it may not be Tim Cook's.