 In their inaugural season of 1972–73, Mikkelson emerged as one of the icetime leaders on the blueline for the Islanders, and posted 1 goal and 10 assists for 11 points in 72 games.In a sign of things to come, he also posted a plus/minus rating of -54, the third-worst mark ever recorded at the time since the NHL had begun recording the stat in 1967.For the 1973–74 season, Mikkelson lost his spot on the Islanders with the arrival of rookies Denis Potvin and Dave Lewis, and ended up spending the entire season in the American Hockey League with the Baltimore Clippers.