It sounds like they aren't breaking problems up appropriately. It also sounds like the team is too large. We have a team size of only 2 developers, but we never take anything over 8 points and we are very cautious about those 8. We also rarely take over about 20 total points per sprint. If they only deliver 40 per sprint don't let them commit to more than that. Something else can always be pulled in later in the sprint if they get done early. Also, "Needs to be delivered by XX date" is almost always a bad way of thinking. It will cause a lot more defects and a lot more problems, and will usually cause the software to be delivered LATER than it could have been. Software is done when it's done. You may want to go back and say, "Well, we can't have the entire project by that date, but what is the minimum that will still be usable?" They will almost always say, "All of it," and then you get to say, "Well, then it will be YY date, at the very earliest, but we can give you (some subset of user stories) by XX date and deliver the rest later."