Lewandowski had a contract with Bayern for a year and Bayern wanted to extend the contract for another year (quite logical given his age), but this was not enough for Lewandowski and he began to rant. As a result, Bayern sold him and I dont think that they were in the red, but Lewandowski lost the Champions League playoffs for the first time in many years. I think he acted like an idiot.
He knows what he was doing by leaving from bayern to the la liga. I thought that if he has a very big faith in barcelona but the fact that if barcelona might be leaving from champion league even earlier compared with intermilan which is still competing in the champion league. As you said that if he has made a very worst decision by leaving from bayern and gone to the barcelona as his new club but i were sure that if he has already considered as of pros and cons when he was moving to the barcelona and so his decision can't be blamed and it's not 100% wrong for him to leave from bayern as he was looking for a new challenge.