Fox being one of the fastest characters and difficult to grab based on his moves, combined with Pikachu's not superb ground game (and Pikachu wants to be underneath Fox), and having the shortest grab range of all characters pulls back the use of his chaingrab. Not to mention that if there's a platform nearby, or an edge Fox can get past, the chaingrab ends (though follow-ups can still happen).
Sheik and Falcon are kind of the reverse of that.
The reason they're limited the way that they're limited is different, but overall they have to overcome the same things. It's just that Falcon doesn't have to try and outrun Sheik, while Pikachu can't catch up to Fox. Pikachu has trouble catching Fox and getting through his defense, Falcon has trouble just getting through Sheik's defense. Both of them equate to not being able to utilize their zero death combos without mistakes from the other side.
If we can assume that one side is making mistakes, then it's only fair that the other is making them too since this is comparing even skill levels. Sheik can easily 0-death Falcon as well, so if we remove the mistakes factor, then we get what the match up really is. Even with mistakes on both players parts, what we get is a << match up.
What we know a character can do in a matchup is based on the top players who have shown how each matchup plays. Our knowledge of any characters options in a given matchup is based on a previous player doing them and succeeding. Saying this chart is based on character and not players is therefore incorrect, since the character is made by it's players.
While we owe our knowledge of the game to previous players, using them as an example and saying they're even skill level with someone else is incorrect. Every game has a winner and loser and people are using characters with different levels of limitation. Taj has the best M2 in the world, but that doesn't mean he won't get outplaced by a Fox who might not be as good of a player as he is. These results most certainly don't reflect skill level. That might be the same guy that Taj JV 5 stocked with Marth. Who knows?
My point is that results are not representative of skill and conditions.
For all we know, M2K and SS could be at the exact same skill level. M2K is using the top 3 characters in the game while SS is using like number 7. It also just so happens that 2 of the characters M2K plays are some of Falcon's worst match ups. I mean look this is kind of Inui Logic I guess, but Jeff beat Armada and M2K's lost to him twice. I'm not saying that Jeff is better than M2K just because he beat Armada, but they have to be playing around the somewhat similar levels if we compare how they did against to Armada.
Yet there are these non-M2K/Amsah Sheiks that do beat the same top Falcons and pretty consistently too. This chart isn't about your chances of 2/3/4 stocking someone, it's about the chances of winning in general, not how bad you destroy them when you do win. I don't think it's fair to say that M2K's results can't be used when he could possibly be the same skill level as the Falcons that he destroys, but just using a better character, while we are taking something like Hax beating some other Sheik (don't know who it was) into account when we don't really know anything about either of their skill levels in comparison to each other. Nothing says that Falcon CAN'T win in practice, hence it not being a <<< match up at even skill levels.
Overall using results is a bad idea although we definitely owe our knowledge of the game to the players. I've seen Falcons win before, but I've also seen Sheiks completely destroy them with more frequency.