Can Dallas ignore what happened in 2013 in DISD?

The DISD Class of 2013 was the last graduation class benefiting from the ongoing progress being made before July 2012.  It was also the largest DISD graduation class in 31 years! 

Then, in November 2013, things rapidly changed.  The official enrollment count for the Class of 2014 recorded the greatest drop year to year in 12th grade enrollment in 29 years!  The Class of 2014 enrollment had lost over 530 students compared with the Class of 2013 enrollment!  What suddenly started happening in DISD?

Dallas ISD Graduation Demographics 1970-2014
(Click on chart to enlarge/print)

Is this record loss in Dallas ISD 12th grade enrollment in any way related to the identical losses that were created in the Harrison School District Two during the last 4 years that Mike Miles was Harrison Superintendent?   During those four years the 12th grade enrollment was constantly dropping while elementary enrollment was constantly rising.  Total district enrollment was therefore stable while 12th grade enrollment dropped over 32% under Mr. Miles.

How was this loss in 12th grade enrollment related to Mr. Miles strategy to develop a core of students with higher grade averages on college readiness tests?  Was he attempting to eliminate low scoring students, students who were not adequately prepared for the next grade? Was that strategy also a factor in the large number of Harrison seniors who transferred to Colorado Springs District 11, to the north of Harrison, where college readiness scores suddenly went down?  

How is this strategy for raising college readiness grade averages substantially different from the "disappeared student" strategy judged by the courts to have been used in El Paso by the now incarcerated former superintendent, Mr. Lorenzo Garcia?