There are a few fighters under the Strikeforce banner that have had issues with UFC in the past and the main reasons they were fighting for Strikeforce could very well have been that Zuffa/UFC wouldn't hire them, Josh Barnett is one, and another Paul Daley got vocal about the purchase after it happened on The Underground:
“Business as usual, what if i dont wanna fight for DANA WHITE/ZUFFA?……Dana white bans me for life from the UFC, Then buys STRIKEFORCE, and thinks im still gonna be EASY and fight on one of the most anticipated fights of the year (vs Diaz)? Which will no doubt make ZUFFA/Dana White money.
Daley vs Diaz still on?…..Someone better holla at my manager real quick.
Not sure what im gonna do right now, honestly…fight for the Strikeforce and be Strikeforce champ, put money in ZUFFA/Dana Whites pockets? Or fight here in the UK for BAMMA, who appreciate my brand, and have my loyal fans, family and media support me. For real.”