Well we used to get a free 100-200 RP once in a while for a holiday or the start of a new season in the original GLB but now the best you can do is get referral points if you don't want to spend money..
They replaced the starting flex with the "free player". Which is much better. It's flex value is considerably greater than the old original starting flex.
As for reward flex on holidays, I can't recall getting any in awhile. The free player is considerably more valuable than all those flex bonuses though.