Houck has the most IP on the team, 37.2. 2d is Sale, 35.1. 3d is Kluber, 34.1. And 4th is Pivetta, 30.2, who gets his 7th start today. If he goes, say, 5.1 innings today, that's 36 IP in 7 starts.
In other words, four of the five starters are a pretty tight shot group in terms of IP. They're all around 5 IP per game.
And that puts a lot of pressure on the bullpen.