There are a lot of factors that go into building a Stanley Cup roster, from good drafting to strong NHL scouting to having the right head coach and system in place.
Managing the salary cap is also a huge part of it.
Every team is looking for bargains when it acquires a new player. And the more players you can get for below market value, the more flexibility you have in building out the rest of your roster and the more impact players you can eventually add.
If you get some bad contracts, though, it can quickly cause problems for building the best possible team.