It's a footballing cliche, but it applies here. The controversial decisions in Thursday's match evened out.
For Chelsea, in fact, that could go all the way back to last weekend.
Last weekend, as you'll recall, Luis Suarez scored a late equalizer for Liverpool as Chelsea drew 2-2 at Anfield. Suarez, of course, should not have been on the pitch after biting Branislav Ivanovic's arm earlier in the match.
A similar argument could apply to David Luiz, who scored the winner Thursday with a well-taken free kick in stoppage time. Moments earlier, Luiz had escaped a red card for a studs-up tackle (he did receive a yellow card).
Suarez's offense was obviously much more egregious, but the same principle applies. A red card is a red, in other words, and if Luiz had seen red, he wouldn't have been on the pitch to score the winner.
Basel shouldn't feel too aggrieved, though. The hosts benefited from a downy-soft penalty call in the second half to score their equalizer.
So, then, the decisions evened out—both Thursday and over the course of the week.