Admission rate outside the context of how strong the applicant pool is does not tell the whole story. For example, College of the Ozarks recently had a 12% admission rate, but its incoming frosh class had an average HS GPA of 3.62 and average SAT scores of 500/534/516 (old three part SAT) and average ACT scores of 23.
http://www.collegedata.com/cs/data/college/college_pg02_tmpl.jhtml?schoolId=1804
Fort Valley State University and Liberty University also have low admission rates, but not especially high stats for their incoming frosh classes.