Brian Matusz will be spot starter in Cubs' series finale vs. Mariners

Jake Arrieta: 'Those two walks put us in a bind'Joe Maddon is giving his five starting pitchers an extra day's rest.

Brian Matusz will be a spot starter in the Cubs' series finale against the Seattle Mariners on Sunday night at Wrigley Field. The Cubs optioned reliever Justin Grimm to Triple-A as a corresponding move.

"We'll use that day however we need to to the best of our abilities," said Jake Arrieta. "We'll find a way to use that day to get some work done and get better and move forward. At this time of year, every one of us might need to refine something.

"It actally might not be a bad idea. Hopefully Matusz is ready to come out and compete and be effective, and we'll move on."

Prior to…