A guy that doesn't like/love the sport probably won't cut it at CL level, its a shame, but he just works for football, he may not put the extra effort beyond his talent and that makes him lose the edge at top level
http://www.mediotiempo.com/futbol/l...tbol-nunca-me-ha-apasionado-tanto-carlos-vela
“Te voy a ser sincero, la verdad a mí el futbol nunca me ha apasionado tanto como para decir ‘soy del Madrid o de equis equipo y voy a muerte’. Claro que prefiero el Madrid pero si no gana no me afecta en lo más mínimo”, aceptó. “Yo disfruto jugando pero al momento que termina el partido, acabó el futbol y me puedes hablar de lo que sea menos de futbol porque no me siento cómodo y no estoy a gusto”
"I'm gonna be honest, the truth is I've never been passionate enough about football to say 'I'm a Madrid/X team supporter and I'd die for them'. I like (Real) Madrid, but if they don't win it doesn't bother me at all" he said. "I do enjoy playing, but the moment the game ends, football is done for me, and you can talk to me about anything except football because I don't like it, makes me uncomfortable"
Also, it doesn't help that he didn't like London either
En ese sentido, mencionó que gran parte de su disfrute con la Real Sociedad se debe a lo contrastante que fue respecto a su vida en Londres, cuando jugaba para el Arsenal y todos sus complejos parecieron salir a flote. “En general nunca me adapté a la vida en Londres, al futbol inglés, no era feliz, no disfrutaba mi día a día y te viene a la cabeza todo: de decir ‘igual soy muy malo, no merezco estar aquí, o estos son mucho mejores que tú’
In that regard, a big reason of why he enjoys playing with Real Sociedad is due to the contrast of what his life in London was, when he played for Arsenal and all his complexes surfaced. "In general, I never adapted to the London life, the English football, I wasn't happy, I didn't enjoy the day to day and everything starts getting into your mind: like saying 'maybe I'm too bad, I don't deserve being here, or these guys are way better than me"
He's a pretty down to earth guy, part of the reason he even grew to dislike football even more was that people knew and bothered him on his private life and he doesn't like that at all. He's a bad cocktail for a team like Arsenal, it attracts undesired fame, he's not in the same level of motivation as a guy like Alexis who loves football, so maybe Vela has the same amount of talent, but he will feel inferior to him because Alexis has the drive to be better than anyone in the sport he likes. Vela seems like a good guy, he knows his limitations in the job and at least found a way to play the sport and earn a nice living balancing everything, he didn't try to scam anyone by trying to come back to Arsenal or other top tier teams just to earn a big payday and then underperform.
Personally, I wish him all the best in his MLS adventure, hope he's even happier there