Overall MK's neutral isn't even poor tho, like you said in your guide. His ground game is excellent and he has all the tools he needs to get things going: burst mobility, safe moves, spacing ability, multiple combo starters. His only real problem is a lack of ways to deal with SH approaches. It's only poor if you compare it to the greats ie. Sheik, Fox, etc. but he has the ridiculous reward and really good disadvantage state to make up for it. If he really had a bad neutral he wouldn't be as good as he is.
Having read over it again, I admit I overstated his neutral disadvantage a little too much. Though it isn't terrible, or bad even, the info is partly relevant, as his neutral is outclassed by top tiers (i.e., the characters he'll be going against most often, like Shiek and Fox as you said). Not too sure about safe moves, though. DA and F-smash are safe, but they're still predictable, and F-smash is telegraphed. D-tilt can be useful for speed, but its range keeps it from being reliable. Again, I overstated, but from my experience, it's overall average, slightly above average at best. The thing is, I mentioned in the guide that a good neutral would make him one of the best in the game, due to his powerful combo ability. Might sound silly, but I'm totally fine if he did have a terrible neutral, because of the greater feeling of reward when you get that conversion. He's a very good character, definitely high tier, but surely not among the very best. Thanks, Jamurai.