The Hoops midfielder scored the equaliser in the 1-1 draw with Fenerbahce in Istanbul last night, but the Parkhead club were already guaranteed to finish bottom of the section after taking only two points from their first five fixtures.
Ronny Deila's side began with a 2-2 draw against Ajax in Amsterdam, before drawing by the same scoreline with the Turkish outfit in Glasgow, surrendering the lead in both games.
Commons believes that proved fateful as the Scottish champions subsequently lost back-to-back games with group winners Molde and then to Ajax at Celtic Park.
Asked to describe the Europa League campaign, he told Press Association Sport: "At times I think we have played really well.
"Other times we have perhaps not played to our ability, but I think when we needed a little bit of luck we didn't quite get it.
"Going back to the first two games, we were disappointed not to get the six points.
"I think we would have put ourselves in a great position if we had but, like I say, we didn't have a lot of luck along the way and especially in Europe you do get bit on the backside.
"The campaign is over so the sole focus is to win the league and if we can pick up the cups along the way it will be a great season."
The Parkhead club had held their own in the Sukru Saracoglu stadium until a mistake in the 39th minute by keeper Craig Gordon allowed winger Lazar Markovic to score.
Fenerbahce midfielder Diego, booked early in the first half after an altercation with Hoops midfielder Stefan Johansen, was shown a straight red in the 67th minute for a kick at the Norwegian, before substitute Commons, on moments earlier for Scott Allan, levelled with a header as the visitors finished strongly.
The former Derby player, back after missing four games with a hamstring injury, believes the morale-boosting win will set Celtic up for the rest of the domestic season.
"It was good to get back," he said
"I have been out for three or four weeks.
"It was good to get some minutes under my belt and it is always nice to get on the scoresheet, but I think it was important that we didn't go there and get beat.
"It kind of puts us in good stead for the rest of the season."
Source : PA
Source: PA