I would definitely would have preferred Sakuragi (iconic sports manga character) over a relatively greenhorn character like Kuroko to rep basketball (face it Kuroko spot was secure since his manga/anime been recently really popular), but having a 2nd basketball centric person as a support character would feel redundant.
Especially when there are different sport Jump manga protagonists like Football player Sena (Eyeshield 21), Tennis player Ryoma ( Prince of Tennis), and soccer player Sho (Whistle!) that can be added for variety sakes.
That said though there is plenty of time left for more reveals and so far been very satisfied with the playable/support selection. They branched out of using only battle manga characters and expanded to Comedy, Ecchi, and Sports which is a +. From the trailers/screenshots they seem to be true to source material. They could add more of the older Jump characters though is my only criticism.