ZNN doesn't know how to win. That must be it, right? It's not that the team won't score runs for him. No. He just hasn't learned to pitch to the game. He's anti-clutch. Trade him for John Lackey! That guy is 12-9 despite an ERA close to 6! The new Jack Morris!
In all seriousness, part of Jordan must be happy he'll be hanging up the spikes in a start or two given the grief he gets put through every start. He has the 11th worst run support in the majors. Take away SF (3 in the Top 9) and Seattle (3 in the Top 12) and you could call him the 6th most unluckiest pitcher out of the teams you expect to score runs this year. He by far gets the worst support on the Nationals (Livan gets the 2nd least support and he's 41st in the league). But it's a funny type of lack of support.
In 15 of Zimmermann's 25 starts the Nats have scored 3 or fewer runs. That may seem like a lot (and it is) but it actually isn't too out of line with what we'd expect. The Nats have scored 3 or fewer runs 64 times this season in 127 games, or roughly half (side note: ugh). Given an equal distribution of bad luck we'd expect Jordan to have 12-13 games of this type. Fifteen is a tiny bit high but not a crazy number.
Where the problem lies is at the other end. The Nats have scored 7 or more runs 21 times this year. You'd expect that they'd have done it about 4 times for Jordan. How many times have they done it? Once. And it was the infamous 14 inning how-many-saves can we blow White Sox game. A game where they had 0 runs after 7 innings and 3 after 9. The Nats never make it easy on Jordan.
Take a look at the 9 games the Nats scored 4-6 runs when Jordan was pitching. You can argue that 4 runs should be enough to win a well-pitched game. In what inning did they end up scoring that 4th run?
Basically the Nats never staked Jordan to an early lead. Even when scoring a decent amount of runs. Every game is tight one for ZNN. I'm kind of glad the Nats are shutting him down. These have been 160 tough innings.