Only 30 publications have fully reviewed Electronic Arts‘ big game of the fall, Medal of Honor, on the Xbox 360 game console. But the relatively weak average rating was enough to send EA’s stock tumbling 6 percent in trading on Tuesday.

Investors are evidently punishing EA because it has focused its comeback in video games on one major metric: game quality. Review scores are a proxy for that metric. The average game ratings of critics are aggregated on the site Metacritic, which shows that Medal of Honor’s rating on the Xbox 360 is a paltry 76. On the PC, 12 reviewers rated the game at 75. On the PlayStation 3, 21 reviewers gave it an average score of 74. User reviews are pretty much in the same category. Not all reviewers, including me, have finished their reviews. But it will be pretty hard to turn those numbers upward as the rest of the reviews come in.

Shares of the Redwood City, Calif.-based company fell $1.05 a share, or 6 percent, to $16.61 a share. The stock had risen 15 percent in recent weeks, mostly on anticipation for Medal of Honor. EA had shelved the Medal of Honor franchise after the disappointing performance of Medal of Honor Airborne, which has an average Metacritic rating of 78. After three years of rethinking and bringing the franchise into the modern combat era, the reboot has pretty much the same lackluster reviews as Airborne.

I haven’t rated the game yet myself, but it didn’t seem that terrible to me. It did compare unfavorably to Call of Duty Modern Warfare 2, but the storyline of the single-player campaign and the multiplayer games are a lot different from the Call of Duty series, as I noted in my preview. Modern Warfare 2, which sold more than 20 million copies, has an average rating of 94.

Despite the weak reviews, EA still has a chance to sell millions of copies of the game, since there are a few weeks before Activision Blizzard’s latest installment, Call of Duty Black Ops, hits the store shelves. The EA game has been controversial because EA allowed players to play the role of Taliban fighters shooting American troops in the multiplayer version of the game. Criticism was so fierce that EA renamed the rivals “the opposing force” instead of the Taliban.

Activision Blizzard’s stock was up 1 percent on Tuesday at $11.25 a share. Logically, if Medal of Honor is really the cause of EA’s stock drop, we should see a corresponding increase in Activision Blizzard’s stock price, as gamers gravitate towards better-reviewed titles.