Get the latest record only on a table relationship

np,

Make a summary field on the Team Member of the maximum of the Effective Date of the Pay Change. Call it like [Effective Date of Most Recent Pay Change]. 

Look that  field up down to the Child Table of pay changes.

Change your existing a summary field which is the Maximum of the Pay Rate include a filter where the 

[Effective Date of Pay Change] is equal to [Effective Date of Most Recent Pay Change.

So, the field will still be a Maximum but there will be only one record which will qualify.  The most recent one.