Think this is overly dramatic. The cardinals have the best record in baseball and are starting Carlos Martinez(4.89/4.93 ERA/FIP) and Tyler Lyons(4.82/2.94). That's not significantly different than Wood(4.96/4.38) and Hendricks(4.65/3.99). The royals have the third best record in baseball. Their 4/5 pitchers are Jeremy Guthrie(5.70/5.16) and Jason Vargas(5.26/5.26). The Yankees have the 6th best record in baseball. Their 4/5 pitchers are Adam Warren(4.65/4.32) and Chase Whitley(3.06/4.40) which isn't quite as bad as Wood and Hendricks but you also have to factor in how terrible Sabathia(5.45/4.39) has been.
Sorry to burst people's bubble here but this rhetoric just isn't accurate. If you'd like to argue that because of other deficiencies the cubs have less room for error than some other teams fine but that opens the conversation up to these other areas where they have been underwhelming. If you want to assign blame you can start with the fact that while Arrieta and Lester(past few starts anyways) have been good they really haven't been dominant. They are a combined 5-5 record wise. From there you can talk about how the offense has been feast or famine. Of the 30 games they have played, 13 games they've scored 2 or fewer runs with a similar 13 where they've scored 5 or more. NL average right now is 4.12 r/g. In other words, they've been very inconsistent and ultimately consistency is how you win games. From there you can go on to talk about things like the bullpen which has been terrible of late. If you look at a team like the Royals with similar issues to the cubs 4/5 starter, they've gotten away with it because they have likely the best bullpen in the majors.
Now that's not to say that at some point you don't look to add another starter. My point here is that most teams in baseball have only 3 or so good pitchers and they are trying to fill out the rest either due to injuries or various other circumstances. Regardless, focusing on starting pitching really isn't going to get you anywhere until july. There's no silver bullets in the minors. Wada, Jokish, Beeler and Turner very well could be just as bad. Edwards is still in AA and hasn't been anywhere close to stretched out for the season. Definitely don't want Jackson in the rotation either. So, until likely the trade deadline this is what the rotation is. However, there's plenty of areas where the team can improve. Scoring more consistently obviously helps. Lester and Arreita dominating would be nice. And hopefully once Ramirez is back the bullpen will solidify some.