Do you have a set of "core values" for you business? Things you would either take a financial hit or fire someone if they were compromised?
Can't remember the author - might be Jim Collins? He stats that we tend to hold on to high producers with low core value fits because they are generating income for you. What they are really doing is poisoning everyone else on the team. Unfortunately I have had a few employees that were fired and after all others said "glad that guy is gone - all he did is *****"
Sounds like your guy is now a low producer and a bad core value fit? Not a good combination...