I don't think Arrieta is in a good shape and no way close to be worth that line against a powerful lineup like the Nationals.
He had that lingering pain in his right hamstring back in September and in about 40 days he only started 3 times where he pitched a total of 10 innings and 7 total earned runs.
If he would have been on a decent shape, I believe he would have started before Lester or right after him, he was injured more than a month ago and I don't believe 1 or 2 days more of rest would have changed absolutely anything.
When you don't have much confidence and you know you gotta face Harper, Zimmermann, Rendon and Murphy you are not gonna pitch with the free full confidence that you should.
The Nationals in 3 games they basically played only 1 inning for real and they are still 1-2 and could have been easily 2-1 if that clown on the bench wouldn't have messed up the 3rd game taking out Max with 98 pitches and not exactly for Andy Miller.
I believe it's time for the Nationals to stand up and start hitting that ball. This Cubbies are no way close to the 2016 Champion team, on G1 they were hitless for 6 innings and an error of Rendon changed the game and on G3 I already said what happened, also there they were hitless for 5 innings.
Roark is no Strasburg or Scherzer or a top one, but like I said this Cubs offensive lineup to me it's not impressive and I believe he can handle it pretty good.
The only two things that I don't like much is the fact that if it's going to be a close/tie game after the 7th the Cubs bullpen it's just better and the clown in the bench could do damages to his own team.
I still believe the Nationals can break the score early and manage this one.
The very first thing that matters when you bet is the line and there's no way the Nationals could be worth +157 against this Arrieta and this Cubs.
I'm 4-2 $8,190 up on the Playoffs, I risk less than 40% of my profit on this one that for me is a clear value.
There are also other considerations that drove me to go strong on this one, but don't ask me more
Hope this was helpful to you..