Arrieta is taking Matusz's place. Manager Buck Showalter wanted to give Matusz a few more days to recover from being hit in the nose by a ball yesterday during a bunting drill. Also, Hammel will only have to pitch once in a National League ballpark, which puts less strain on his right knee.
Hammel's next turn wouldn't come until after the June 21 off day, when the Orioles host the Washington Nationals the following night. Hammel won't have to bat and run to first base - or walk back to the dugout.
Arrieta didn't find out he was starting until today. Perhaps he'll benefit from having less time to dwell on it.
Matusz will fly out to Atlanta tomorrow.
A decision on Endy Chavez's status probably will come tomorrow. He avoided the disabled list today, but Showalter doesn't want a short bench for games in Atlanta and New York.
The Orioles could go in a few directions if Chavez is placed on the DL. The first choice appears to be recalling infielder Steve Tolleson, who wouldn't have to stay down for the minimum 10 days.
Outfielder Nolan Reimold will undergo an MRI today or tomorrow in Baltimore.
Joel Pineiro and Dontrelle Willis will pitch in a simulated game tomorrow at the Ed Smith Stadium complex. Pineiro is scheduled to go five innings, with Willis covering the last four.
Matt Lindstrom threw on flat ground today from 60 and 120 feet for eight minutes without any discomfort in his right middle finger.
Miguel Gonzalez is scheduled to start tomorrow night for Triple-A Norfolk.
Left-hander Josh Hader, the Orioles' 19th-round pick in the First-Year Player Draft out of Old Mill High School, officially signed today and will report to Sarasota.
And finally, the Orioles' game against the Tigers on July 14 at Camden Yards has been moved from 7:05 p.m. to 4:05 p.m. to accommodate FOX.
The Jim Palmer sculpture will be unveiled at 2:15 p.m. as part of the Orioles Legends Celebration Series. Ballpark gates will open at 2:00 p.m.
Fans holding tickets for July 14 who are unable to attend due to the time change may exchange their tickets at the Orioles Box Office or send their tickets to Baltimore Orioles, ATTN: July 14 Exchange, 333 W. Camden St., Baltimore, MD 21201. Ticket exchanges can be made for any remaining non-prime game this season and must be completed before July 14.