he has room to improve in problem solving skill, espectially when it takes multiple steps and it need ability to connecting dots to get to the next level in his career.
I think assigning a mentor to him might be helpful. (這裏看你自己想不想。想的話,自薦一下,你就成他領導了。再把自己手中的活推掉一些。因為你要花時間照顧他。)