Lamar (15-12, 6-7 Southland) led by as many as 14 in the second half.
Miles was 11-of-18 from the field and 2-of-4 at the free-throw line. McThay made three 3-pointers and all but one of his 10 free throws. Jay Brown scored 14 points off the bench and pulled down eight rebounds for the Cardinals.
Lamar led 37-31 at the half.