After a stretch where he has given up 14 earned runs over 14 1/3 innings his past three starts, Arrieta has been working on some slight mechanical adjustments with his windup with pitching coach Rick Adair.
Manager Buck Showalter said there is a clear reason why Adair approached Arrieta with the adjustment.
"Fastball command," Showalter said. "The walk totals are the thing that has gotten him in trouble. The stuff is not an issue. Saw that with Jeremy last night. Fastball command opens up a lot of ways to be successful.
"Not many guys are going to throw a better curveball than Jake. He has a live fastball, but you have to get it in the right spots. It gets magnified when you play the type of offensive teams we have played this month.
"You go back through the games and I can show you, there are places to go on guys with the fastball, but if you miss location, you will pay the price," Showalter said of some recent Arrieta starts.
Arrieta is 9-6 with a 5.10 ERA on the year in 19 starts. But, in his first nine starts this season, he was 5-1 with a 4.03 ERA and seven quality starts. In his last 10 starts, the right-hander is 4-5 with a 6.18 ERA and just four quality starts.
The Orioles are trying to find a way to have Arrieta improve his command and control and the results should improve with that.
"Stay on line and body control," Showalter said. "You have to repeat a delivery and you have to repeat it 100 times (each game) to get it right. Once you find something, you stay with it."
Arrieta is 0-1 with a 6.75 ERA in two career starts against the Red Sox and in the series recently in Boston, he gave up six hits and five runs against Boston in 4 1/3 innings.