Why TJ Ward tho?

Seems like a good player. Im not sure why Tandy is losing his job (judging by snap counts that is the case). We heard all year how communication was a problem for our safeties and adjusting to Mike Smith's system. At the end of the year last year, Tandy and Conte were making big time plays and the defense was thriving (especially Tandy). I understand solidifying debt, but does it make sense to do that at the cost of having to reestablish that communication and losing the familiarity on defense? Tandy was clutch for us down the stretch last year IMO.