Pretty simple message here and I'll let Zach Strickland describe it below in his own words for FreightWaves.
The basic principle is when the going gets tough, contract carriers may get going. They reject contract rates to move to the spot market and when spot rates move down they are more than happy to handle the contract rates they rejected previously.
That is, of course, unless you develop great contract relationships. But a key piece of developing those relationships lies in the steady, consistent, and plentiful volume they need.

***Tender Reject Indices are measurements of carriers' willingness to accept the loads that are tendered to them by shippers under contract terms. It is expressed as a percentage of loads rejected to total loads tendered.