Rafa didn't win that Europa League the team won it, just like they manged to get to the CL final back in 2008 under Grant
I think this is a statement purely out of bias.
Rafa is the manager of the team. So he picks the team, gives the tactics, so how does he not receive any credit ?
So let's say if Chelsea finished in 5th spot and got knocked out of the Europa 2nd round, then I guess according to your logic, it was never Rafa's fault either, it was just the players.
But no, if that had happened, then you woul all gladly blame Rafa.
You can't just simplify the role of a manager.
He has a big role to play in motivating the team.
In fact I would go on to say that Rafa is one of the major reasons that Chelsea won the Europa League.
This Chelsea team would be the least motivated after having won the CL and got knocked out in the 1st round, they would have just sulked and got knocked out early in the Europa League.
Most of the top teams don't even try that hard in the Europa league.
But it was Rafa who kept pushing the team to perform and finally win it because at the end of the day it's a European trophy.
I'm not saying that Rafa is the best manager in the world, but he's surely there in the top 10-20 managers of world football.