I also think, and there have been more opinions like this in the past years, that Alonso is maybe the fastest driver when the car is not good, he can extract 110% of midfield cars, but when the car is good, guys like Hamilton or Vettel are better. Also that he can't make a team work, he can be the #1, but not a very good team player.
I'm sorry, but that really doesn't make any sense. Your driving abilities don't magically become worse as the car gets better.
Also, Vettel's appearance doesn't turn a car that was designed during the time Alonso was still at the team, good all of the sudden. By that logic, Alonso's efforts last year lead to the car improving this year, which is nonsense and it's obviously just the reshuffling that has lead to some early results.