In what year did the only team to beat the Houston in the final round of postseason series games earn its lowest ranking?
beat the Huston refers to tmIDLoser = 'HSM';  in final round of post season refers to round = 'DSF'
SELECT T2.year FROM series_post AS T1 INNER JOIN teams AS T2 ON T1.tmIDWinner = T2.tmID WHERE T1.round = 'DSF' AND T1.tmIDLoser = 'HSM' ORDER BY T2.rank ASC LIMIT 1