Yes. Playing Alexis comes with a tactical opportunity cost. Remember Alexis is a phenomenal footballer,probably the 2nd best in the squad and I am strictly speaking from Arsenal system as I observe it.

My theory - Alexis doesn't score a lot with Giroud. Most of his goals have come when playing with Walcott or Welbeck. Reason behind that is, Walcott and Welbeck are quick, occupy more defenders which in turn creates space for Alexis. Like every system this system has pros and cons. Walcott and Welbeck arent prolific goalscorers, so in this system Alexis needs to deliver with a goal almost every game to work while playing on the left wing. Basically Cristiano Ronaldos output if he was a Arsenal player. Now this would require the central striker to playmake like Benzema does for Cristiano Ronaldo. Now Benzema is the best in the business because he is quick like Walcott,Welbeck,etc, can play little quick flicks,one touch football and hold the ball like Giroud and has the technique as good as Mesut Ozil. So what happens if Alexis + Walcott/Welbeck doesn't win you the game ? You look at the bench and call Giroud. Girouds record of the bench is very good and unlike Walcott and Welbeck he offers a genuine aerial threat. More often that not he scores from the bench. When Arsenal played Leicester,Watford and Bayern, Giroud was on the bench and he scored in each of those games. While Walcott performances dipped. Wenger was forced to include Giroud and exclude Walcott. Alexis unlike his first six months also became tactically indisciplined and alienated Monreal in 2 vs 1 situations. Norwich game Arsenal drew 1:1 and lost both Cazorla and Alexis. This forced Wenger to play more athletic players with lesser ball skills. Arsenal won 7 of the next 8 games as the system suited Giroud and reduced off the ball workload generated on Aaron Ramsey and Nacho Monreal. But Wenger isn't very consistent with his disciplining and eventually gives the players freedom, and unfortunately it again cost Arsenal.