Ok so I’ve played shuma since he came out, I’ve placed top 16 at majors and played against the best players around. I will tell you why shuma is low teir.
There is a very underlying fact about this game that most people are unaware about. In this game what ends up being one of the most prodominate importance of determining how good or tier list spot of character is, comes down to priority. Characters with good move sets and some effective abilities are still generall considered lower tier if it gets out ranged/beaten out by other character priorties. Its the reason vergil, wesker zero etc are all so good. Yes they have good moves, but they can basically press buttons all game relatively safely knowing they will win the priority war. Now of course this is not the be all of tier list, as some characters can compensate this with strong zoning or some other gimmick.
That being said lets talk about shuma. As most of you realize by now, outside of c.m,c.h shuma has no priority, meaning he can’t aimlessly push buttons against other characters. Also shuma has on the poor end of air grab length and his best air normal is not an airgrab normal. Also his mystic smash if a free grab or AA for most of the cast. This means in air to air combat shuma gets heavily beaten by any character that can easily mash f+H like mags or Zero. Then you take into effect how slow his ground speed is, meaning he can’t be a ground pressure/speed demon like x-23 or wolvie, so he has to take to the air regularly. Then his air dash is so slow/vulnerable you are basically taking a gamble they don’t punish it with a jumping heavy or special. Now factor in that he does not have the zoning or specials necessary to force an air character to fight grounded, or ground character in the air, he is basically forced to fight his opponents game. So this means generally your game will break down around methodically moving in or getting an assist to make it possible to get in. Now once you are in, you don’t even have the tools to stop them from escaping. Now shuma does have some ok mixups, but they basically require you to be pointblank to do it, and to be truely effective you need a strong assist to make sure they don’t just chicken block out, which you prolly needed that assist to get close enough to try and set this mixup up.
There are plenty of finer points to the above argument, but most of them usually break down to very specifics like the list of save moves that straight out beat our mystic smash etc. If you really want to know why shuma is bot tier. I’ll pick 3 characters I never play, Vergil, Mags Dr doom, and I’ll beat your shuma in a straight up battle effortlessly. Now I knows its a team game and all, but the fact that you have no chance in 1 v 1 's like this is a huge part of why he’s bot team. There are several other matchups I could list just as bad these just tend to be most popular three.