I don't think this is realistic since all of his numbers have been improving. He was worth 3 WAR in 2018 and 2.8 in 2019, improving peripherals in pretty much all major categories over the last 3 or 4 years. Also I think just getting out of Detroit was a huge boost to him. OPS'd over 1000 while playing with the Cubs.
I don't hate Calhoun if he is brought in as an addition to Castellanos, I just don't want him in the lineup every day. I don't think it's wise to have a streaky unimpressive hitter get 500 ABs because of his handedness. Obviously this is just my opinion but he has a much higher bust potential than Castellanos and we can't really have a black hole in RF again, even if it's 1 year.