I think Mario's real problem right now, besides tourney rep, is that he has to rely on his Bair for decent range. It's not a bad thing, I mean at least he has a good ranged move, and he does have fireballs to help, but I feel like his lack of mixups for ranged moves is what's hurting him right now. Mario's Bair is pretty fast and lagless to the point of being able to instantly FF and buffer directly into jabs, but it would help if he didn't have to overly rely on it. Mario's Bair might be enough if it came out about 2 frames faster, but 6 frames means it'll be used a lot like how most characters use 6 frame Bairs, or possibly how MK uses his Fair. Just some food for thought, because that is honestly Mario's largest flaw right now.
People tend to generalize the fact that Mario has poor range overall to the point of forgetting that he has any ranged moves at all, but the fact is that Mario simply lacks a good variety of ranged moves. I really wish Bair was all that Mario needs, cause it is close to being that since it's so safe, but without at least some kind of reliable mixup with similar range Mario will be held back, or at least become more and more unpopular. Mario has potential to be great, but there really needs to be a solid strategy to keep him less linear. I mean honestly, someone with frame advantages that rival MK's does not deserve low tier.