Surely a bit depends on injury / fitness assessment of both Ben Brown and of Tom McDonald.
IF (emphasize if) Tom has been carrying an injury that has caused him to fall from a match winner / leader in 2018 to his 2019 and 2020 situation, and IF that injury / fitness issue is regarded by experts (not just Demonland posters) as having fully recovered, then maybe Brown could be regarded as surplus.
And vice versa, should Brown’s 2020 be related to an injury that he is carrying that does not look like resolving, then would we want him.
I am certain that there is a lot more going on than meets the eye.