Washington is 19-5 against Boston since 2015.
And many of those wins Boston had were by Halak. Remember the 5-0 drubbing opening night? Or the countless times the Caps have beaten Rask? I think Rask has like 1 win against the Caps in the last 4 years.
mcubed.net : NHL : Series records : Washington Capitals against Boston Bruins
Washington is 5-3 against Boston in the 2020's.
Washington is 28-12 against Boston in the 2010's.
2021 is the only year Boston and Washington have been even (2-2) in the last 7 years. Before that, Washington has had a record over .500 over Boston since 2015. In fact, from 2015 to 2018 Washington finished 3-0, 3-0, 3-0, and 3-0 against Boston.
From 2014 to 2019, Washington set an unprecedented and series high 14 game winning streak against Boston.