One reason Dortmund has not been exceptional after most seasons is in their practice of selling off their star players, because they make more money from that maybe it makes up for the trophies they have been unable to win, because I have not heard of them having financial struggles too often like I hear with other teams. If they keep Guirassy this season for aa reason, he my be sold next season except they keep having more good reasons to keep him.
May be the reason why they do sell those players is because they do it as precautionary approach not to have financial problems, most team initiated survival techniques and that has been keeping them in the business of football but I don't think doing this consistently make any sense because this will get the fans pissed, it is a good idea for any organisation or club to plan financially but it also has to to be balanced, do you say make up for the trophy they weren't able to win? How possible could that be, they should come up with other strategies too, they need trophies, the need to improve their games to achieve that, so they don't have to rely on one strategy, if Guirassy prove them wrong, they may not have any option than to keep him