Not just fast players, I think it is more of a matter of tactics employed by the opposing team and Bayern's response. Bigger/elite clubs will not easily score this type of goals against Bayern because even though Bayern tends to play a high line, against bigger/elite teams they will be more conservative and will not push up that high. Against smaller/weaker teams who tend to park the bus and give up possession and play really compact in the back, Bayern tends to push up really high which leaves them exposed often, especially when they don't have enough midfield protection. Essentially something that happens to a lot of elite teams, I think. Of course, the quality of their defenders is not helping either.