I think Shai's really good. Solid offensive player who's a dog defensively. At the same time, I think he's sort of maxed himself out as a player.
Where Tyrese is concerned, while I'm not sure he'll become the Brandon Roy-esque player Shai is, I think he'll continue to develop both physically and offensively (though a lot of his offensive struggles sort of came down to him not having an NBA body yet) and, more importantly slot in next to Fox much better than Shai ever could as an elite secondary guard/facilitator. Also, we won't have to pay him max money for another three years.