This is off DLNET:

We have notified Pinnacle Airlines of our election to terminate its Delta Connection contract effective July 31 because of performance. We expect the operational pull down to be orderly and have minimal impact to our customers.
“Our customers rely on Delta and Delta Connection carriers for outstanding service, and we will continue to insist on that level of performance from our business partners,” said Don Bornhorst, s.v.p.-Delta Connection. “Pinnacle’s operational performance has fallen below minimum levels required under the contract. Today, it’s more important than ever that Delta and its Delta Connection partners meet operational and customer service levels.”
We have an agreement with Pinnacle to operate 16 CRJ-900 aircraft, nine of which are in service. We’ll choose another connection carrier to operate the former Pinnacle routes.
Pinnacle has operated as a Delta Connection carrier since December 2007.