I really like their offseason. They added Renfroe, Drury, Urshela and Phillips to the lineup/bench along with O'Hoppe at last year's deadline. Add in Rendon who gave them nothing last year and that's going to be a colossal improvement with basically 6 guys being added to last year's lineup/bench. In most of those cases those 6 will be replacing negative WAR players.
On the pitching side they added Tyler Anderson (coming off a 4 WAR season) and a couple of mid bullpen pieces in Estevez and Matt Moore. Altogether, that's a TON of additions in one offseason.
As for the rotation depth don't forget Jose Suarez who is a legit backend rotation piece too so 1-5 they are pretty solid. They've also got some decent depth with Tucker Davidson (probably the last guy in their 6 man rotation) Silseth, Chris Rodriguez, Griffin Canning, and others in AAA and AA who could give them something. That won't really "wow" anyone but if you compare it to the depth around the league it's probably better than most.
They are definitely WC contenders.