I also have 'flea flicker' but have not been able to get 'double slants.'
I had over 200 Domination duplicates on my bench and I never completed the set. After trading in some Gauntlet cards I was finally able to complete the Domination set. Maybe I'll complete the Gauntlet set before they issue the next version of the game, maybe not.
One thing I know for sure, EA wants you to spend money buying stamina refills to replay the events. Doing so won't get you the cards you need. I learned that one the hard way.