Charlie McAvoy wouldn't be where he is today without the guidance and leadership of Zdeno Chara. Chara took McAvoy under his wing immediately, and it is still paying dividends for the American-born defenseman. While the Boston Bruins attempted to use the same strategy for Mason Lohrei, he wasn't able to take on the responsibility of playing on the first pair with McAvoy early in his career.
After Lohrei's defensive struggles last season, the Bruins knew that something needed to change. It was clear that he wasn't yet able to carry a pairing on his own, a situation that arose due to the injuries to McAvoy and Hampus Lindholm.