The first mistake is that you're watching Game Grumps for the gameplay content. It might be a "Let's Play" channel, but the draw is in the commentary. Half the time they don't even play. I remember a number of times (especially in Sonic '06) where they would spend at least half the episode just aimlessly wandering around, and I didn't even notice until one of them pointed-out that "Oh crap we should probably actually do something" because I was just listening to their banter. Sometimes I don't even watch the show, I just put it on and start playing my 3DS with its sound muted.
As Arin mentioned once (I honestly couldn't even try to tell you which episode or even which game), the show was originally planned as a podcast before they decided to make a YouTube channel and actually show the game being played, so it isn't a shock that they aren't making much of a point to necessarily do well in the games.
As Arin mentioned once (I honestly couldn't even try to tell you which episode or even which game), the show was originally planned as a podcast before they decided to make a YouTube channel and actually show the game being played, so it isn't a shock that they aren't making much of a point to necessarily do well in the games.