I will even go pre NRL era and say 1981 for the Roosters, after finishing as minor premiers after smacking Parramatta in the 2nd last premiership round then not winning a game after that.
In the last premiership round they lost to Wests by 2 pts, hardly a blip at the time as they were already Minor Premiers and would still have the week off,
Playing Parramatta in the Major Semi, a very ill disciplined Easts side kept dropping the ball, game was 0-0 at half time and Easts scored first minutes into the second half and it looked like plain sailing from there but Parramatta scored twice to take the score to 8-5 before Ron Giteau went over in the corner and had a side line kick to win Easts the match and straight into the Grand Final, the kick missed so scores were tied 8-8 at full time and in extra time Parramatta kicked two penalty goals to win 12-8.
The following week Easts probably left their worst performance of the season playing against Newtown, in a really dour match Newtown had the better of play overall and had a 10-5 lead late in the match, still at that point it was still tight and the game could have gone either way, with 7 mins to go Marty Gurr threw a beautiful pass to Steve McFarlane who spilled the pass with no one to beat with the try line in front of him and the chance for Easts to level up and possibly win the match was lost, still there was time left and Easts threw the ball the ball around madly and dropped the ball and the ball was kicked through with Ray Blacklock scoring the match winner 15-5.
They way 1981 ended for Easts was dismal and heartbreaking as they were the dominate team throughout the premiership rounds,