Their final position of 10th is their lowest in Super League since their debut season in the competition back in 2007, when they finished 11th, just avoiding relegation.
They have reached the play-offs for the past three seasons under the stewardship of Justin Morgan, but finished five points adrift this term.
Sandercock’s injury woes continued in Saturday’s final league match against London, as Rovers lost hooker Lincoln Withers with a suspected ankle ligament problem.
The coach told the club’s official website: “We’ve used 33 players this season and I’ve never in my life used that many in first team football.
“I’ve never had six of our starting seven in the backline not play due to injury so our luck certainly can’t get any worse next season.”
Rovers lost nine of their last 10 games to miss out on a spot in the top eight, and attention now turns to recruitment for the 2013 season.