Hi there,
As we see, you have lost around 300 domains which are linking to you...so every metrics above "Total Linking Root Domains" is quite logical. You should search which those domains are? Maybe you had backlinks in some RSS domains or so.
As I know, unfortunately Moz Open Explorer don't have an option for users to see their lost backlinks. Search the web, there are some similar services that have this option.
Cheers,
Milan
P.S.
Be aware that you have bad ratio between "Linking C Blocks" and "Total Linking Root Domains" -> 23/143