To be honest, I don't know where you saw a good performance from Barcelona in the Champions League. The fact that they had chances to score a goal against Bayern and against Inter also does not mean some good achievement - every team has missed chances. Yes, Barcelona did not lose all the games with a crushing score, but all the games were lost by game - in general, it is clear that Bayern and Inter are simply stronger than Barcelona.
And yes, the bookmakers give about 16% for the fact that Barcelona will still be able to reach the playoffs. For me personally, it's amazing - Inter should beat Victoria, Inter can beat even unmotivated Bayern. While even an unmotivated Bayern can beat their favorite principle rival - Barcelona.
Barcelona have poor performance in Champion League after drop to 3rd standing position and left 3 points behind Inter Milan the latest position qualify to next round, bad dreaming for Barcelona at champion league because next match if Inter success win actually Barcelona have to play on Europe League. Become bad started for Barcelona before el clasico match because the rival team Real Madrid have lock one place at 16 round of Champion League. Actually I think chance for Barcelona have closed because Inter playing home on next match and seems easy how to win from Plzen.
Whatever bad achievement in champion league Barcelona have forget it and keep forward and preparing for el clasico match, this games not only with 3 points achievement but will be most crucial achievement if can't defeat Real Madrid at Bernabeu.