TP to the OP.
For the people who their principle is to never overspend on player, you have to understand the exception to the rule here.
Project what will happen in the next 2 years... all the top teams and the top destination city will have money to spend. It is easy to realize that during this 2 years, if Boston is not a contender in the east, we'll have almost 0 chance to get a good player. I mean, FA will go to top teams and the trade market will be dead (any team will be able to resign their top players without any concern with their cap space). So we'll end up with the left over players.
To sum it up, if you are not overpaying this year, we'll end up adding average players during 3 years at least.