Nintendo has not had a good past few days, despite its original superstar Mario finally hitting the iPhone.

The company’s shares have dropped about 15 percent in the past five days, which once again shaves off a rather significant amount of the company’s market cap. On the year, Nintendo’s still up by more than 50 percent, but we can see below that it’s a rather lukewarm reception from Wall Street compared to the rather spectacular spike the company saw after Pokémon GO launched in July (charts from Yahoo Finance).

Here’s where it is on the year so far:

On day one, Super Mario Run — the company’s first Mario game for the iPhone, which was widely hyped at an Apple event and across the App Store — was download more than 5 million times. But the app, despite hitting the top of the Apple iOS top grossing charts, was extremely frustrating for customers, whether that was a result of an always-on internet connection requirement or the small amount of demo content available before users had to purchase the full game for $9.99.

In many ways, it may seem like Super Mario Run for the iPhone could be seen as a bait-and-switch. Super Mario Run sits at the top of the App Store — but it’s under the “free apps” section. The top rankings offer some of the greatest visibility for apps, and it’s an extremely coveted place to gather additional momentum and users and potentially create a positive feedback cycle. For Super Mario Run, and users, it would seem three levels is probably just not enough to qualify the app as a true “free” app in the same way that Pokémon GO was.

But, these are both mechanical or optics issues for Super Mario Run. I do believe there’s another core fundamental element to it — unlike Pokémon GO, the game just simply isn’t as revolutionary, and it’s getting hammered for not only being just a decent game but also some extremely sharp pitfalls to actually get into the game. And Wall Street is already well aware that gaming companies are a hits-driven business, whether that’s on mobile or on proprietary consoles.

I’ve been playing Super Mario Run for a couple of days now, and the always-on requirement is definitely a tough pill to swallow. Aside from that, the app just really feels fine. It’s a side-scrolling runner that adds a few basic flourishes. The two I’d point to first are the vault — Mario basically skips over a few small obstacles streamlining the run — and the little spin Mario does to slightly extend his jump (which is often required to hit the top of a flag pole at the end of a level).

What it does feel like, in retrospect, is something that is nowhere near as revolutionary or polished as one of the original side-scrolling runners — Mirror’s Edge from EA for the iPhone 4 — felt like. While Super Mario Run feels like a decent game, Mirror’s Edge felt like something really special. It offered some replayability in the sense of finding packages, as well as ways to sort of increase your level of mastery of the levels with different ways to handle guards. And the game, for its time, looked absolutely stunning too.

In a shameful twist, Mirror’s Edge is no longer available for the iPhone, and many won’t be able to size up how Super Mario Run sits next to Mirror’s Edge. And that, honestly, is a tragedy — it’s a fantastic piece of gaming history that I believe really helped raise the bar for what games on the iPhone needed to look like and feel like. And it really helped the iPhone feel like a unique gaming device that could invent some new feeling with different interactions other than tapping virtual buttons.

So what we have here, it would seem, is two branches. The first is, maybe Mario simply isn’t as big as the Pokémon brand, or not as beloved, so users are less forgiving. The more likely scenario is that users are less forgiving of the game because it isn’t up to the same standards of design and polish that Pokémon GO had at launch, despite Niantic stumbling many times along the way. The Pokémon brand offers a multiplicative effect for the potential growth of an app, but the game still has to be good.

Wall Street, on the release of Pokémon GO, offered Nintendo a rather spectacular amount of leeway. It was an opportunity to give the company the benefit of the doubt that, if it released games of the level of Pokémon GO with its biggest franchises, it would crack open a market of hundreds of millions of players that don’t have access to its consoles that cost hundreds of dollars. The Wii U (or Switch) are optional, but a smartphone is a requirement (whether or not you argue that the iPhone is a premium product or not).

If all this is the case and the argument holds, Nintendo simply can’t just hang out. It has to produce games that meet a certain level of quality because iPhone owners are demanding as much polish as the other top games on iOS. Minecraft, Candy Crush and Clash of Clans are all good games that work well on the platform (well, Minecraft rounded up to yes) because they represent good mechanics that are highly polished and adapted well for the iPhone as well as offering hooks that really keep users engaged.

Super Mario Run, again, is simply fine. And fine isn’t good enough. Wall Street, more or less, has known this for a while. Gaming is a hits-driven business, and a crappy series of launches for Call of Duty could spell disaster for a company like Activision, or an inability to continue to introduce good new content for games like Destiny and World of Warcraft. The fate of Square Enix, one of the most prestigious brands in gaming history, you could argue also hinges on the success of future Dragon Quest games and Final Fantasy XV.

Nintendo may have caught a break when it saw a big spike from Pokémon GO. It really offered some insight into Wall Street’s observations of companies like Nintendo and the growth that a new strategy offered. But like Zynga or King, you can build a big business out of a big hit, but that strategy needs to be highly repeatable. Nintendo, even with its cherished brands like Pokémon, Mario, Zelda and Metroid, needs to keep the hits rolling and not simply assume bringing these games to mobile — the largest potential audience Nintendo has ever seen — in mediocre fashion will keep people happy.