Sturridge was pulled back when he had a chance of getting 1 on 1 with Vorm. To me it was far more a penalty than the one vs Lucas. Lamela was going nowhere and threw himself to ground with minimal if any contact from Lucas.
Lucas kicked Lamela 5 times before he went to ground, therefore there was 5 lots of contact, it was a clear penalty and pure stupidity from Lucas.
The Sturridge one was a penalty as it was a clear pull back, however unless you go to ground referees will very rarely point to the spot.