That's my worry too. From a completely objective (and uninformed) point of view, it would be easy to say, "She said she didn't then, she's saying she did now, which one is it? She's lying just to get out of her contract. Not guilty," and I've seen MANY comments on TMZ articles and such along these lines.
When you look at the bigger picture though, the fact that there are so many timestamps for these occurrences (2014, 2013, now 2011) all detailing the SAME abuse, the SAME allegations... all pointing to the same exact timeframe of when the abuse allegedly happened, the details of what was involved (rape, drugging, waking up in the bed sore etc.) provide evidence that these allegations aren't recently fabricated.
I just hope that the Jury will see past Luke's dirty play and realise the TRUTH.