Yes.
First of all, neither Contreras nor Gray are “marginal” players, unless your definition of “marginal” means “not superstar”.
Contreras OPS+ of 123 makes him a good replacement for the OPS+ of 128 they lost in Bregman. If Contreras is a dumpster dive, what exactly did they lose in Bregman?
Sonny Gray was a 3.5 fWAR pitcher brought in to replace Lucas Giolito, a 2.0 fWAR pitcher. So if Gray was a dumpster dive, what was Giolito?