Crouch announced his decision in nominating the Saints as his club of choice on Wednesday, with the Victorian club looking to go the extra distance next season and push for the flag.
With Crouch and his heavy salary set to land in Moorabbin, the Saints will look to shed some weight in the form of Roberton and Webster.
Roberton finished second in the Saints’ best and fairest count in 2017 but has battled fitness and heart-related setbacks since 2018, playing just one game in 2020.
Webster didn’t feature for St Kilda this year after failing to break into the side after ongoing injuries.
The 27-year-old is understood to have attracted some interest, while Roberton, 29, still hoping to return to peak fitness.
The Crows could force the Saints into a trade if they are to match the offer made for their star midfielder, with St Kilda’s first draft selection at 14th overall.