Tier lists are made from a MLG/tournament view, are don't necessarily determine how popular a character is.
Also Carl is more common then Arakune IMO
Yeah now that you mention it, i dont recall fighting anymore than 1 Arakune but i have fought atleast 3 or 4 Carl players. 1 of which i played earlier who mains Carl and played over 10000 matches with him (Ranked and Private). He was really good. Too bad any respect i had for his skills was lost as he joined a genuine beginners lobby just to show off with relentless attacks. He raped the host twice. Absolutely destroyed him. But when it came to me, and i wasnt so easily punished, he would spam all low hits then jump back and repeat just because i wouldn't let him combo me. I dont mind losing. I even created an expert lobby so i could train a bit with experienced players. Got my ass kicked constantly. But it was fun. I have no respect for good players seeking easy wins in beginner lobbys though.