It is difficult to identify what caused the bark damage.  When trees are stressed due to poor drainage, planting too deeply, drought. soil compaction, etc.  they can be susceptible to insect and disease issues.  These issues are usually secondary and are not the reason for decline.  It is possible the tree may have had insect issues and the bark was compromised by woodpeckers looking for insects but we cannot say for sure.  
Regardless of the cause, the tree should be removed.  Keep your trees well watered during dry periods and keep mulch away from the base of the trunk.
For an onsite diagnosis regarding the health of your trees, contact a certified arborist http://www.treesaregood.org/
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