Captain Tom Anderson, in-form midfielder John Bostock and long-term injury absentee Fejiri Okenabirhie are among 13 players at the Eco-Power Stadium whose contracts are about to expire.
Rovers are set to exercise an option to extend Anderson’s contract, McSheffrey revealed on Thursday.
There are 15 players still under contract for next season and, with that in mind, several out of contract players look set to be released this summer following the club’s impending relegation to League Two.
“It’s more or less sorted with one or two question marks still,” said McSheffrey on the retained list.
"We have got a big squad and lots of numbers and we have probably got too many numbers than starters.
"We need to make some decisions as we have a lot of players contracted for next season already.
"We have a decent enough core squad and quite a big squad. So it is trimming it down and adding quality in the priority areas that we feel we need.
"There will be three, four or five renewal offers out there as we do want our best players to stay.
"But we have to take into account that we have a big squad and some players might not want to stay at the club.”
Louis Jones, Ben Bottomley, Cameron John, Branden Horton, Ben Blythe, Lirak Hasani, AJ Greaves, Dan Gardner, Aidan Barlow and Ed Williams are also out of contract this summer.