Lappin, 26, split last season between the New Jersey Devils and their AHL affiliate in Binghamton. The native of Geneva, Ill., has registered eight points (5g, 3a) in 60 career NHL games and 123 points (67g, 56a) in 168 AHL games.
Polei, 23, posted 20 points (9g, 11a) in 53 games for the AHL's Bakersfield Condors in 2018-19. The Wetaskiwin, Alta., native added three points (2g, 1a) in 10 playoff games.
Vecchione, 26, put up 38 points (15g, 23a) in 67 games for the AHL's Lehigh Valley Phantoms last season. The Saugus, Mass., native appeared in two games for the Philadelphia Flyers in 2016-17, but was held scoreless.
Walker, 25, has appeared in 12 combined NHL games for the Washington Capitals and Edmonton Oilers, accruing one goal and one assist and becoming the first Australian to play in the NHL. He has collected 140 points (60g, 80a) in 300 career AHL games, all with Hershey.
Pouliot, 25, spent the last two seasons with the Canucks, posting 12 points (3g, 9a) in 62 games in 2018-19. The Estevan, Sask., native has totaled 48 points (8g, 40a) in 200 career NHL games with Vancouver and Pittsburgh.
Dotchin, 25, spent the last season with the Anaheim Ducks, posting one assist and a minus-4 rating in 20 games played. The Cambridge, Ont. native has appeared in 103 career regular-season games over three seasons in the NHL, posting 23 points (3g, 20a).
In addition, the Blues have signed the following players to AHL contracts: Cam Darcy, Zach Nastasiuk and J.J. Piccinich.
