Pool Member Flaps count

There is no statistics which reflect the number of times a pool has been up or down. Adding an iRule would for this would be a lot of overhead for little gain. The best way to monitor this is using SNMP Traps to your monitoring platform. It should record when a pool was up or down and you can compile stats from that. If you don't have that option the simplest way is to watch the log files for pool up and down messages. Then you can figure out stats from that as each entry will have the time when it changed.

tail -f /var/log/ltm | grep pool_name