Lets not forget how we dominated them for the first 35 mins at home, if we play at our best they wont be able to live with us, it's just going to be hard to get a performance of that level with the amount of games we've had to get through(also perhaps the upcoming games on their mind will play a part) and the atmosphere away to Napoli.
Chelsea vs Roma was different they could have lost their game and never looked like they could run away with it even when ahead. They went 2-0 up themselves but they didn't have the level of dominance in that game we did, we should have really put the game to bed by making it 3 or 4. In the long run I think it's better we didn't kill the game off because I think games like this are double edge sword our players will be tested both mentally(concentration, positioning etc) and physically more than most teams will be able to do yes(going to need extra efforts to recover legs after it) but they will potentially sharpen our game and bring us on to another level, one that can beat Real, Barca, PSG and lift the trophy.
In short we play our best team in this game, as this is a game the team want learn from and win(if we lose fair enough but we still learn), listen to what Pep says about constant improvement these are the games where you learn things. There's nothing different about Arsenal this year that's short term and they aren't anywhere near this Napoli side tactically.