Something would have to cataclysmically go wrong offensively for them to be bad there. Last season they had 3 players who were regulars over .350 OBP(Rizzo, Schwarber, Bryant) and another 3 over .340(Fowler, Montero and Coghlan). They then went out and added Zobrist(career .355 OBP and .359 last year) and swapped in Heyward(.353 career .359 last season) for Fowler. That's how deep their offense is and obviously that says nothing for improvements from Russell, Baez and Soler.
Things could spiral out of control if their pitching gets hurt. But here's the thing, if there's an area of the team they are looking to improve going forward anyways it's starting pitching. So even if they do happen to lose a starter and have to make a trade for one, it's not a case where it's entirely just to replace an injured guy. And really, I think you'd only be worried about Arrieta and Lester going down. Maybe you throw Lackey into that but Warren was a solid back of the rotation pitcher. Wood was their #5 last year. Cahill has been a solid starter in the past. Edwards you probably stretch out and maybe let him start in AAA. And obviously you have Pierce Johnson also likely to start in AAA. That's as deep as you can realistically hope to be at the back of the rotation. The only issue is there's not really any top end talent there unless you talk about Edwards breaking out or possibly Johnson doing the same but from my understanding of the scouting grades he's a #2 absolute best case and probably not realistically even more than a #3.
So, like I said if Arrieta or Lester go down maybe that entices you to slightly over pay for someone. I don't know for certain who will be available near the deadline but we've already heard Jose Fernandez's name come up in trade talks. Carassco and Salazar haven't moved. Tehran hasn't moved. None of Cobb, Odorizzi, Moore and Smyly have moved. Strasburg will be a 2017 FA if memory serves so if Washington is bad next year he might move. SD still hasn't moved any of their starters. So on and so forth. There's a lot of pitching that might move at some point. And with Baez and Soler the cubs have 2 MLB ready pieces that if we're being honest aren't necessities for their future. Obviously you'd keep them if you can but you'll still have a very strong offense without them. And while lacking some top end talent the cubs have a crap ton of depth in their farm system right now.
