What is the meaning of the values returned from listStatistics method in the "jboss.jca:service=ManagedConnectionPool" MBean in EAP?

Issue

Below is a snapshot of the JDBC metrics for one of the JDBC Datasources (worst one) observed during this problem. I assume the 2 sub pools exist because we're using XA drivers with separate pools. Not sure we understand what the "Total Block Time:1055" represents.

Sub Pool Statistics:

Sub Pool Count: 2

Available Connections Count: 100
Max Connections In Use Count:1
Connections Destroyed Count:0
Connections In Use Count:0
Total Block Time:0
Average Block Time For Sub Pool:0
Maximum Wait Time For Sub Pool:0
Total Timed Out:0

Available Connections Count: 99
Max Connections In Use Count:10
Connections Destroyed Count:264
Connections In Use Count:1
Total Block Time:1055
Average Block Time For Sub Pool:3
Maximum Wait Time For Sub Pool:1
Total Timed Out:264