MIA is about in the middle seniority wise. from a quick glance is looks like this order from junior to senior:
ANC
HSV
CVG
LAX
MIA
JFK
PAE
IAH

there might be a slight variance to that list, plus or minus one spot but with the exception of ANC, which is way junior, and PAE and IAH which are really senior, the rest are able to be held around the 1 year to 1.5 year mark currently.