I see 2 consecutive starts a couple of months ago in which he gave up 15 Earned Runs. Those 2 starts did indeed happen, let's not deny that, but they have a disproportionate effect on his ERA relative to the other 16 starts. His ERA was 5.60 after those two starts at the end of May and has been coming down since. Other metrics are solid (K/BB, etc) from what I've read today. (edit to add: as noted by Harmonica below while I was typing this)
Also even if he is an innings eater, a solid 3 or 4 starter innings eater is quite valuable in itself, and something the Cubs desperately need now and beyond. I think he's a good bit better than that description.