Lens are a decent team, no more than that.
They have power, pace and athleticism and were well organised on the night.
To get a result against this current Arsenal team, you need to defend well, and you need to take advantage of any mistakes in transition, break quickly and take your chances. They done that, so fair play to them, no real complaints about anything, i thought a draw would be more a fair result but they did well so congrats to them.
Think we are a bit naive at times still, need to sometime accept at times away from home in Europe, that if you are struggling to win the game, then at least don't lose the game and stay compact.