Packet Loss, Delay & Jitter

I'm not a networking guy but I know that the ping check does include packet loss check, but that is for the ping packets that the collector itself is sending and not just any packets. For Windows and Linux the TCP Stats DataSource provides some retransmit stats that might help. Perhaps monitoring switches can also provide some details too.

In general this sounds more like something you may need to troubleshoot more actively than just LM doing once-per-min collection of stats from the OS/device. Perhaps try using iperf?

IPSLA between your Cisco devices.