Sanford was right at home when he scored the biggest goal of his NHL career. The native of Salem, Massachusetts, got the final goal for the St. Louis Blues in their 4-1 win against the Boston Bruins at TD Garden in Game 7 of the 2019 Stanley Cup Final.

Sanford was selected by the Washington Capitals in the second round (No. 61) of the 2013 NHL Draft after he had 36 points (12 goals, 24 assists) in 37 games for the Islanders Hockey Club in the Eastern Junior Hockey League. He played for Waterloo in the United States Hockey League in 2013-14, getting 35 points (17 goals, 18 assists) in 52 games, then played two seasons at Boston College, where he had 63 points (20 goals, 43 assists) in 79 games.

Sanford made the Capitals out of training camp in 2016-17, making his NHL debut in a 3-2 shootout loss to the Pittsburgh Penguins on Oct. 13, 2016. He scored his first goal (a game-winner) in a 6-4 victory against the Anaheim Ducks on Feb. 11, 2017. Sanford also scored in the following game.

On Feb. 28, 2017, Sanford was traded to the Blues by the Capitals along with forward Brad Malone and first- and second-round picks in the 2017 NHL Draft for defenseman Kevin Shattenkirk and goalie prospect Pheonix Copley. He had three points (two goals, one assist) in 26 games for Washington and five points (two goals, three assists) in 13 games for St. Louis in 2016-17.

Sanford's development took a step back when he dislocated his left shoulder during training camp before the 2017-18 season. He played 20 games and had seven points (four goals, three assists) for San Antonio of the American Hockey League. But Sanford was healthy in 2018-19 and finished with 20 points (eight goals, 12 assists) in a depth role, then had four points (one goal, five assists) in the last five games of the Cup Final.