I think Tina is on the verge of being low tier.
To be honest, I'm not that fussed about tier rankings. I'm sure you already know this, but the moment you're in high level competition, any character can be very dangerous. My point is, in the right hands, all characters can be very strong.
Just as an exaggerated example, let's say there's a character that has poor follow ups and really slow attacks (let's go as high as 100 frames for attacks....why not? lol). But his counters and throws are in line with other fighters. If a player is amazing at reading the opponents moves perfectly (another exaggeration), in theory, the match can be won by using throws and counters alone. Yes, it's challenging and not ideal, but it's possible. (I'm just using this silly example to make a point).
There's a popular player in the street fighter circles that won a tournament using T-Hawk just to prove this point. So while tiers are relevant to point out which characters are more usable, dish out better damage, have better frame advantage...etc... The player should really be added to the formula (not easy to do).
Anyways, I'm sure this topic has been hashed out elsewhere. But I just thought I'd respectfully share my opinion because I see tier talk almost everywhere here and it's given more weight than it deserves.