Interestingly according to BTSport going into the game, Exeter's lineout was the second worse in the tournament this year with only Munster worse. However I imagine part of Exeter being so low is they have had more lineouts from penalties and so more chance to lose. However while it is a strength, teams know they will use it and will target it defensively as well. I'm all for using a strong weapon, but you need variation as well and if a couple of penalties had been kicked then the pressure would have been greater on Munster to keep in touch and so take more risks, as well as giving Exeter more chance to counter attack. On top if Exeter had kicked a few to have a 6 point lead or so then Munster would also have been more wary about giving away penalties in their half. Instead they could compete more, especially at the breakdown, because they knew they would have more opportunities to defend the lineout and maul which they had been doing pretty successfully.