Hammers teammate Declan Rice spent eight years at Stamford Bridge as a youngster before joining West Ham in 2014.
Speaking to WHUTV alongside Rice, Fredericks remarked: “You were somewhere c*** before, weren't you?
“Oh yeah, you got released (by Chelsea). Their loss, isn't it? Now you're top boy.
“Your (FIFA rating) was a big disrespect as well. Oh wow, 69 after a full season of Prem, bossing it, pocking all sorts. Interceptions got to be up there in the 90s. Next year rating in the 80s, no?"