Which coach had the highest winning rates in the 2009 season? What's coach's nickname.
the highest winning rate refer to divide(W, sum(W, L))
SELECT T2.coachID, T1.nameNick FROM Master AS T1 INNER JOIN Coaches AS T2 ON T1.coachID = T2.coachID WHERE T2.year = 2009 ORDER BY CAST(T2.W AS REAL) / (T2.W + T2.L) DESC LIMIT 1